Blue Line

Mastering the art of trustworthy testimony: Twenty-six lessons for police officers

October 20, 2023  By Gilles Renaud

Photo credit: © TERACREONTE / Adobe Stock

The 26 lessons that I offer in this article to police officers are brief, focused and dedicated to improving their ability to provide credible and reliable testimony. For the sake of brevity, we’ll jump right in.

Lesson 1: Earning the reputation of a trustworthy witness

The first lesson draws attention to how one may earn the reputation of being a fair witness.

In 1978, as a law student, I saw a trial and heard the judge state in his conclusions that the police officer, having inspected his vehicle earlier, clearly assumed the drugs found in it later were hidden by the accused, since they were the only person transported. The officer then whispered to the Crown that he made a mistake, was invited to testify further, and said, “I now recall that I switched cars,” a fact not written in his notebook. Not being able to say if this car was searched, a doubt arose. The man declared guilty five minutes earlier was thus acquitted.

This officer no doubt was praised by the judge later as the story was told to other members of the judiciary and earned the reputation of being a fair witness. The same must have happened in terms of talk involving the Crown Attorney’s Office and the Federal Prosecution Service, not to mention the Defence Bar and the staff. Thus, if a mistake found its way within your testimony, it must be brought to the attention of the prosecution and, thereafter, be disclosed and communicated to the Court.


Lesson 2: Over-egging the pudding by exaggerating

The second lesson draws attention to the concern that the police witness is either exaggerating the negative acts or demeanour of the defendant or, equally of concern, is failing to highlight neutral or positive words or actions.

The oath includes the words “… the whole truth” and a police officer must not therefore exaggerate testimony, such as stating that the defendant cursed a dozen times unless you counted these acts. You cannot say, “it went on for twenty minutes,” unless you timed it. You must be precise and must not embellish. To the same effect, if the defendant stopped cursing at some point, or ceased to blade their body, or did something neutral, it must be brought out in your evidence.

Courts expect the unvarnished truth and you do not wish to develop the reputation of always appearing to enhance information, especially when your colleagues will have described the event in more subdued terms. If you were spat upon three times for certain, state it in no uncertain terms in your evidence; but if you cannot say if it was more than thrice, without real fear of mistake, limit your evidence to what you know for certain.

Lesson 3: Police officer’s notes to refresh memory

The third lesson addresses the fundamental justification for the resort to police officer’s notes: to allow them to refresh their memory from an aide-memoire each one created (and not through a collective action) when their memory was fresh and when they still possess an independent memory.

This is an excellent summary:

“It should be remembered that an officer’s notes are not evidence, but are merely a testimonial aid. Trial judges routinely tell officers on the witness stand that they may use their notes to refresh their memory, but that they must also have an independent recollection of the events. To elevate the absence of a notation to a mandatory finding that the event did not occur would eliminate the officer’s independent recollection from the equation. The notes would become the evidence.” (R. v. Antoniak, 2007 CanLII 53233 (Ont. S.C.J.), at para. 24.)

Please consider the emerging viewpoint that the more complete are your notes, the less you need to tax your memory.

Lesson 4: Notes versus independent recollection

The fourth lesson draws attention to the concern that the police officer deliberately failed to note something of importance, by reason of the fact that they enjoyed an independent recollection of the event.

Generally, police officers may only consult their notes as an aide-memoire if they possess an independent recall of the event. By contrast, the failure to record an important fact at the time of making of the notes, purportedly because one possesses a memory of the event, is typically seen as evidence of “covering up”. All that you saw during that event is in your memory shortly after. To attempt to explain an omission in your notes by reason of the fact you recalled it should mean you had no reason to note anything. If your notes are incomplete, admit it.

This subject requires a 5,000-word lesson, but this brief review seeks to stress that if you failed to note, for example, that the suspect spoke with a pronounced accent, and it becomes an important point at trial, your facile response that you had no reason to note it as “you would never forget that fact” would apply to other things you did note, such as they drove their car directly at you to seek to escape.

Lesson 5: Police officer’s notes as a form of disclosure

The fifth addresses the emerging judge-driven concern that police officers’ notes should augment defence disclosure.

“… officers’ notes are provided as part of disclosure …” (Machado, 2010 ONSC 277, para. 121.)

“… police officers could not withhold disclosure of crucial evidence on important points by saying ‘I didn’t note it because I would remember it’. Zack is a case about disclosure … in that case the foundational observation of unsteadiness on the feet that was the basis for the opinion of impairment and demand [was absent] – the police can’t keep aces up their sleeve…” (R. v. Golubentsev, [2007] O.J. No. 4608, by Duncan J., who wrote R. v. Zack, [1999] O.J. No. 5747.)

Please consider the emerging viewpoint that the more complete your notes are, the less likely is it that a disclosure argument will emerge. In addition, I used to read the notes before a judicial pre-trial regarding impaired charges and if they were sparse, I might recommend to the Crown that this was a poor case.

Lesson 6: Police officer’s notes not complete – testimony not reliable?

The sixth lesson discusses the so-called rule in Zack that has been largely misunderstood.

The defence du jour respecting notes is expressed this way: “Not noted, not reliable!” In fact, in Golubentsev, [2007] O.J. No. 4608, Duncan J., who wrote Zack, [1999] O.J. No. 5747, relied upon as the basis for this view, stated, “My own decision in Zack is often relied in support of an argument to the effect ‘If it’s not in the notes, it didn’t happen’. That is not what Zack stands for…” And, “… there is no law … that an officer must record everything … to comply with the Crown’s disclosure obligation…” (Machado, 2010 ONSC 277, para. 121.)

Police officers are not stenographers. But if you fail to record something vital, a disclosure issue may arise, leading to an adjournment, and there is always the danger that something not noted will leave a judge in doubt whether you recall it well.

Lesson 7: Police officer’s notes: guidance from the Supreme Court of Canada

The seventh lesson reviews some observations from our highest court.

From Wood v. Schaeffer, [2013] S.C.J. No. 71:

64 – [T]he duty to make careful notes … is an important part of the investigator’s broader duty to ensure that those who commit crimes are held accountable …

65 – [Note-making] is not a burdensome task that police officers must reluctantly undertake because they were taught to do so at their police college. It is an integral part of a successful investigation and prosecution … The preparation of accurate, detailed and comprehensive notes as soon as possible after an event has been investigated is the duty and responsibility of a competent investigator…

Surely, you all wish to be described as competent and professional investigators.

Lesson 8: Not noting vital information is troubling

The eighth lesson seeks to ask and answer the question, “Why would one not be as complete as possible, respecting vital information?”

Many cases include references to “no notes” or words to that effect. In Palmer, 2009 ONCJ 23, paragraph 62 reads, “Although not put in his notes, the officer testified that he recalls the doctor said something to Palmer to the effect of ‘Oh, I hear you’re going to give me some blood,’ to which Palmer replied to the effect of ‘Like [expletive] I am, I’m out of here’.”

How could the officer not note a statement? These words came to light during a pretrial meeting with the Crown shortly before the trial commenced. This omission invites an hour of cross-examination.

Please make full notes to give judges all of the needed tools at judicial pre-trials and the defence full disclosure.

Lesson 9: Cross-referencing voluminous notes – highly recommended

The ninth lesson draws attention to the relatively rare example of a police officer preparing an index or detailed cross-reference of all the notes, for ease of locating information.

The last trial I prosecuted prior to becoming a judge involved a first-degree murder in the Youth Court, and my last witness was a quite experienced forensic officer who compiled voluminous notes and an index of the over 2,000 photos he had taken, chiefly of blood drops to establish the route of the unfortunate victim of a stabbing. The officer had no difficulty in 1994, before smart phones and tablets, in locating any information I or the defence wanted. The few hours he took preparing the index saved much court time and established his high degree of professionalism.

I have not seen any such detailed list of documents or cross-reference on times, places and things but I highly recommend that you prepare one, especially given the ease of retrieval by means of computer programs.

Lesson 10: Reducing the stress of cross-examination by means of training

In this lesson, I seek to make plain that this type of instruction seeks to reduce the stress associated with cross-examination by assisting you to understand and to testify fully and fairly.

I consider the passage that follows valuable:

[The] criminal justice system is a source of dissatisfaction and stress. … In the courtroom, [police officers] report being subjected to rigorous cross-examination by defence lawyers, which is felt to be stressful (Prof. R. Loo, September 1984 – “Occupational Stress in the Law Enforcement Profession, Canada’s Mental Health, 10-13.).

By way of partial prescription to remedy this situation, I suggest that increased education on the subject of court testimony and opportunities to experience such stressful situations during training, and to discuss the experience thereafter, must surely be beneficial.

In our adversarial system, police officers are expected to provide oral testimony in which their verbal skills and ability to think on their feet, so to speak, are of foremost importance. Some consider this an unfair expectation, and all think it highly stressful. Thus, all opportunities to study this element of police work must be pursued.

Lesson 11: Certainty in your evidence versus typical actions

The eleventh lesson draws attention to the concern that the police witness is foolishly substituting the qualifier “certainty” for the more likely qualifier “I am duty bound to”, and has undertaken certain actions in accordance with your training.

I have often witnessed police officers testify that they are positive that they took a certain vital step, such as informing a detainee upon arrest of the rights to counsel, even though they made no note of this step, adding “I always do so” or “I was trained to do so” and would never overlook this requirement. If you failed to make a note, now some time has passed between the event and the trial, and you were involved in multiple other such situations, I urge you to be cautious. State what your belief is, certainly, but be fair.

Without a note that you did what your training requires, and absent a recording or equivalent “no doubt” independent information, I suggest that you avoid the “makeweight” kind of phrase “I invariably do so”, as you should write notes about such vital information, but you failed to do so.

Lesson 12: Reversing the proposition

The twelfth lesson draws attention to the typical cross-examination tactic of inviting you to look upon the situation you encountered from the opposite perspective.

Be mindful that it is typical (and proper) for defence counsel to suggest that you misunderstood the scene that you examined, especially as you saw it from the wrong perspective. For example, if you came across a person holding a bloody knife by the hilt, and the knife was in a body, you would think this is the assailant. Counsel will suggest you would have thought it innocent if the person was a surgeon, helped by paramedics. Often, in impaired cases, it is suggested that alcohol was spilled onto the defendant. Prepare yourself by considering all sides of the question.

This type of concern, such as the spilt alcohol, must be considered at the scene, and subsequently at trial, according to the circumstances. You must rule out innocent explanations for possible criminal acts. That said, if asked fair questions, you must respond fairly and not merely dismiss possible scenarios as being speculative until you have given the matter fair consideration.

Lesson 13: Being challenged by means of a reasonable scenario

This lesson draws attention to the typical cross-examination tactic of suggesting an alternative scenario to the one you concluded was the actual situation, and which justified the accusation(s).

I recall Justice Giamberardino defending a man charged with possession of a stolen car, as a passenger. The arresting officer testified that two men were reported to have been seen stealing it a few miles away and that he saw the car turn east onto Second in front of Ecole Secondaire Citadelle, as he drove west. The future judge asked if reliable information placed his client at the scene of the theft. The reply, “No”. Next questions was, “Can you swear that my client did not just hitch a ride just before the street corner, that you could not see?” Same response.

Chapter 25 of Melville’s Moby Dick includes a passage with the words that an advocate defending whaling would refer to “substantiated fact”, but could also put forward “a not unreasonable surmise, which might tell eloquently upon his cause…” This states the law of cross-examination on this point quite fairly: a lawyer or self-represented person is entitled to suggest a scenario that may be consistent with the objective facts. It need not be true, and the officer must never allow the fact that a fair answer may result in a reasonable doubt arising cloud their judgment in framing their answer.

Lesson 14: Big words – big deal

The fourteenth lesson draws attention to the somewhat rare cross-examination tactic of deliberate resort to multi-syllabic or rare words with a view to confusing or embarrassing the witness.

There is a joke that lawyers are fond of saying in which the police officer is asked: “Was my client (pick one): otiose, verbose, morose, adipose, grandiose, bellicose …?” The object is to have the officer respond in a positive or negative fashion, it matters not, to then confront the officer with their understanding of the word, to show (it is hoped) that the witness will not admit confusion or lack of knowledge. If you do not know the meaning of a word, do not hesitate to say so. You will be seen as both candid and reliable.

I recall being asked by a judge, when working for a legal aid clinic in law school and before I studied evidence, if my question was consonant with such and such a rule? I stated that I neither knew the rule of evidence nor what consonant meant. The judge took pity on me and left me alone… Later, as a Crown in a first-degree murder trial, I asked my law clerk what “copacetic” meant. In other words, judges will sympathize with an honest “deer in the headlights” look.

Lesson 15: The rule in Browne v. Dunn

This lesson draws attention to the confusing so-called rule in the 1893 case of Browne v. Dunn that requires lawyers to inform adverse witnesses of the substance of what will be called by way of testimony or documentation to show that your evidence is not worthy of belief.

Defence counsel (and the Crown, when dealing with defence witnesses) must provide a fair opportunity to any adverse witness to respond to the impeachment information they propose to call. For example, you might be cross-examined at an earlier stage in your cross-examination and challenged in general about your prejudice vis-à-vis persons who are Toronto Maple Leaf fans, buried within other general themes. Typically, towards the end of the cross, counsel get some latitude to go over some of the same terrain on the implicit (or clear) basis that defence will call specific evidence, such as showing you burning a team flag.

It is impossible to draw clear lines, but most judges will be reluctant to hold against a witness information contradicting their testimony if they were not given a fair chance to show that the information is wrong. For example, you were trying to stop a flag, set on fire by others, from burning.

Lesson 16: Testimony of police officers not presumed credible or reliable

The lessons that I offer police officers are brief, focused and dedicated to improving their ability to provide credible and reliable testimony. This lesson draws attention to the simple fact that a trial judge in a criminal trial (as well as in quasi-criminal prosecutions such as in the case of Provincial Offences) may accept all, some or none of the testimony of a witness, including that given by a peace officer.

I easily recall a conversation I had many years ago with a “white-shirt”, who asked me why the judges were no longer accepting the testimony of peace officers as being inherently more trustworthy than that provided by civilians, including the defendants. He noted that the judges seemed to need a reason to justify preferring the evidence of police officers when it conflicted with that of a non-police officer. My response was that no class of witness is presumed better than any by reason of the status of the person testifying, but excellent notes might be essential to the outcome.

Police officers are not considered inherently infallible or superior witnesses as that would upset the presumption of innocence. Their outstanding and complete notes, however, may tip the scales in satisfying the Court as to which person possesses an excellent memory of the event.

Lesson 17: Defence counsel insisting on ‘yes’ or ‘no’ answers

The seventeenth lesson addresses the vexing issue arising when defence counsel suggest that you must respond with a ‘yes’ or a ‘no’ to their question(s).

I find that there is no cut and dried response, as many judges consider that it is proper to insist on such a response, but only in the clearest of cases. No unanimous opinion has emerged in attempting to identify this elusive category of cases. As for me, I have a fundamental belief that the court cannot ask a witness to testify in such a way that they are encouraged to breach their oath or solemn affirmation. Thus, if the question requires the witness to provide nuances or qualifications, then those elements of testimony must be allowed to be given.

Police officers are encouraged to respond as they believe their oath requires them to, and if defence counsel insists on a one-word reply, after you have stated that it is necessary for you to respond otherwise, you must allow Crown counsel to intervene on your behalf.

Lesson 18: “Do you still beat those you arrest?” type of questions

This lesson addresses this type of fundamentally unfair question as it takes for granted that you have engaged in disreputable conduct in the past.

This type of question is addressed differently in a case without a jury, as judges disabuse their minds of improper questions or responses daily. Assuming there is no jury, defence counsel must present a foundation, at the very least, such as a disciplinary accusation, though no finding has been or was made. And, even then, the unfairness may be so extreme depending on how broad the question is framed that the Court may simply direct the witness not to respond. Again, Crown counsel may object.

Some wise judges have suggested that the best answer is for the police witness to say “No” and for the trial to move ahead. Other judges may prohibit the question without a foundation on the grounds that there is no fair basis to suggest such misconduct. At the end of the day, Crown counsel may intervene, but it is for you to defend your good name.

Lesson 19: One question too many in cross-examination

In this lesson, I address the troublesome issue of counsel cross-examining so closely that you are prevented from offering the full account of what you wish to describe in testimony, until one too many questions is asked of you.1

Consider this transcript of an arrest at night:

Lawyer: And you say you approached to within 12 feet of these men without their seeming to notice your arrival, sergeant?

Officer: Yes

Lawyer: In a totally empty square at two in the morning?

Officer: Yes

Lawyer: Nobody else around was there?

Officer: No

Lawyer: Normal … pavements…

Officer: Yes

Lawyer: I mean you didn’t approach over a lawn or grass of some kind, did you?

Officer: No

The witness was not able to testify freely, until asked how he got so close silently:

Officer: On my bicycle

In our adversarial system, the apparent unfairness of being tightly “boxed in” during the cross-examination is justified by the fact that Crown counsel has full liberty to draw out all of this information in examination-in-chief and may re-examine if this information is led during cross-examination but cut short of the “bicycle” part.

Lesson 20: Friendly cross-examination – be wary of

In this lesson, I draw attention to the rare case in which defence counsel call you as their witness, for example in a Charter application, and you are then cross-examined by a Crown.

I recall a defence disclosure application in which a veteran detective was called by the accused. The prosecutor then asked leading questions in cross-examination, to demonstrate the fairness of the investigation. The detective never looked at his notes, though he did so often during the examination-in-chief. In effect, he left me with the distinct impression that he was allied with the Crown, at every level. I gave almost no weight to the results of this one-sided “friendly cross-examination” as it was not balanced and not the result of critical faculties being applied in a critical way.

You might never encounter such a situation but if it arises, consider your oath and your duty to fairness and justice. All questions involve the application of your judgment and of your critical faculties.

Lesson 21: ‘Think dirty’ and being unfair in cross-examination

In this lesson, I warn police officers not to act as Dr. Charles Smith did when he testified, as he famously stated that he was taught to ‘think dirty’ in evaluating a situation and attempted to never make allowances for a defence theory, presumably carrying this negative view of matters into the witness box.

I defended with success a 12-year-old who was wrongly accused of killing a 16-month-old child she was babysitting. Of note, the local police never bought into the theory espoused by Dr. Smith that the child was shaken to death. The point is that you cannot answer questions put to you in court, and be true to your oath, if you refuse to be fair in considering innocent or neutral possibilities as to the facts. If you ‘think dirty’, convictions are likely to follow, as will be appeals, wrongful convictions investigations and Judicial Inquests to ensure that truth and justice emerge.

You might never encounter such a situation but if it arises, consider your oath and your duty to fairness and justice. All questions involve the application of your judgment and of your critical faculties.2

Lesson 22: Comparative and superlative cross-examination

In this lesson, my focus is on the type of cross-examination that “pits” you against your colleagues and, as well, that sees you rank your successes.

Defence counsel may ask you to describe your rate of success in terms of arrests, recoveries, issuance of search warrants, etc., with the view of having you compare yourself with your “lesser” colleagues. Further, to invite you to state how your work in each file was superlative in the sense that it was your best work and, as well, superior to what anyone else could have achieved. Ultimately, the submission will be made that you are too cocksure to be relied upon to have investigated fairly and that you seek to charge persons to promote you career, not justice.

It is not unfair to ask you to qualify the challenges you faced in resolving a file but be wary that you not be viewed as cocky and a glory hound. As that famous detective Joe Friday stated, just state the facts.

Lesson 23: Demeanour of the police witness – murderous looks

In lesson 23, my focus is on the demeanour that an officer presents during their testimony.

A text published in 1908, The Rights and Duties of Judges and Pleaders, by Alex J. Balm, includes these remarks at pages 98-99: “The police witness … salutes the judge and boldly steps into the witness-box … He then looks murderously at the unfortunate accused …” This citation serves to make plain that the judge (and jury) are typically going to focus attention on your words and your looks – and if the latter raises suspicion as to your true character, your words may be assigned no weight. Be honest and professional and never look askance at anyone, being polite to all.

Everyone expects police officers to be professional in both appearance and action.

Lesson 24: Cross examination in nine vital areas

In this lesson, my point is merely to highlight that there are thousands of articles for defence counsel to study to assist them when they seek to impeach your testimony.

In one article,3 we read:

Your cross-examination of the police officer requires consideration of …

  1. Official reports …
  2. Police methods and duties.
  3. Personal characteristics, credibility, memory.
  4. Knowledge and opportunity for observation.
  5. Partiality towards own investigation.
  6. Testimony on matters not contained in reports.
  7. Courtesy and fairness.

In the final analysis, all such lists will focus on your training and professionalism.

Lawyers will prepare at length to challenge your testimony and you must be diligent in learning the lessons about testimony that you are taught throughout your career.

Lesson 25: Cross-examination and ‘ruffling the feathers’ of the witness

In this lesson, I briefly address the issue of intimidation by defence counsel.

I quote this valuable advice on this subject:

… some counsel … set out to “ruffle” the witness in the hope that he may give hasty answers or lose his composure … it becomes increasingly vital to maintain the calm, unhurried dignity of the competent police witness throughout … counsel may ask [unfair] questions … the witness should be quite sure that he fully understands the question before he answers it. Again, counsel may frame a lengthy question. Then it is prudent to consider well before answering. If necessary, the witness should ask, “Would you please ask that question again, sir?”4

Police witnesses are unfairly called upon to demonstrate a degree of verbal prowess in court from time to time and it is only fair that they be instructed as to what traps may be set for them, notably the brow-beating counsel.

Lesson 26: Cross-examination to prove the police officer is lying

In this lesson, I turn my attention to the sad reality that some officers have been demonstrated to have lied to the court, and that defence counsel are of the view that a vigorous cross-examination may be the only vehicle to achieve that objective.

An excellent article contains this nugget of information:

… if the police claim they heard a scream in the middle of the night, who can testify that the event never occurred? Or if an unknown caller tells police someone is dying in apartment twelve, how can a defense attorney verify if that is true or not? By allowing emergency searches based on hearsay or reports from unknown sources, the courts have put an almost impossible burden on defense attorneys to prove that the policeman is lying. Defense attorneys can attempt to meet this burden in several ways. Investigation in these cases is crucial. The only real weapon the defense is likely to have is cross-examination. He or she must make the most effective use of that weapon possible…5

Police witnesses might well complain of the rigours of cross-examination and in response, I suggest that if they are the unfortunate victim of a false report, they will be glad that their lawyer is able to impeach falsehoods by the accuser by means of a vigorous cross-examination.


  1. Referencing an excellent article: “Police detectives’ perceptions of giving evidence in court”, by Mark R. Kebbell and Caitriona M.E. O’Kelly, (2007) 30(1) Policing: An International Journal of policing Strategies & Management, 8-20, at page 10.
  2. v. Doyle, 2023 ONCA 427, released by the Court of Appeal for Ontario on June 13, 2023, includes these remarks at para. 1: “This is another in the long list of wrongful convictions brought about in part by the unreliable expert evidence of disgraced pathologist Dr. Charles Smith. [Footnote 1 reads: Cases in this court setting aside such convictions include R. v. Mullins-Johnson, 2007 ONCA 720, 87 O.R. (3d) 425; R. v. Sherrett-Robinson, 2009 ONCA 886; R. v. Kumar, 2011 ONCA 120, 268 C.C.C. (3d) 369; R. v. Brant,2011 ONCA 362; R. v. Shepherd, 2016 ONCA 188; and R. v. Blackett, 2018 ONCA 119.”
  3. See “Cross-Examination of the Police Officer in Accident Litigatio”, by Aaron J. Broder and Marie M. Lambert, in Legal Essays of the Plaintiff’s Advocate, (1961), edited by Robert Klonsky.
  4. Refer to “Giving Evidence”, by Inspector F.A. Gordon, (1964), 37 Police J. 481, at page 483.
  5. Refer to “The Police as Good Samaritan: Constitutional Dimensions of the Emergency Exception to Search and Seizure Doctrine (Part 2)”, 3 Police L.Q. 37 (1973-1974), by Robert Fortier, pages 37-47, at page 44.

Gilles Renaud was formerly a Judge of the Ontario Court of Justice from 1995 to 2023, and an Assistant Crown Attorney (Ontario) and a Prosecutor, Department of Justice (Canada) from 1990 to 1994. He is happy to answer any questions or received comments at

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