Canadian Criminal Trial Advocacy/Developing a Theory of the Case



Developing a Theory of the Case is the most important step in trial preparation. It organizes the entire presentation and argument in court.

The Theory of the Case is a summary of what the party believes happened that logically fits with all the evidence that is expected to be presented to the court and which will lead to the conclusion that the party desires. In other words, it is a narrative that should convey the whole story that the lawyer wishes to advance.

A more colloquial way of understanding a theory of the case. It is like an elevator pitch. It is the summary you tell a lay person who asks what your case is all about where you want to convince them they should be on your side.

The theory is useful as it should guide the lawyer at every step of preparing the case, including trial strategy. Without a theory of the case, there is no real unifying strategy at trial and nothing for the trial judge to follow. It leaves the case entirely to chance and the lawyer will not be able to control the direction of the case and so will not be able to lead it to the desired conclusion.

The theory should paint a full picture of the events including parts of the events for which there is either no evidence to prove it or the evidence is inadmissible.

For the defence, the theory will typically either focus on a counter-story to the one proffered by the Crown Attorney that presents a lawful sequence of events or alternatively simply focus on the procedural defects in the Crown's case. While for the prosecution, the theory will typically focus on the premediation and ulterior motives of the party.

Even though the legal analysis of the judge does not permit him to simply chose between competing stories, in actual practice that is largely what is being done, where to theories are being presented to the judge. Thus, the more comprehensive, logical and appealing theory will always win over the lesser theory.

Elements of a Theory


It is not a theory to simply state that the accused was not present at the time of the offence. The theory must be more comprehensive, explaining all of the

There are three main elements of a theory of a case:

  1. it must be factually logical and fit common sense
  2. it must satisfy the legal elements needed to win
  3. it must appeal to the emotions of the trier-of-fact



The narrative that makes up the theory should consist of all the "facts beyond dispute", which are the good and bad unquestionable facts that will inevitably come out in court. If you do not, account for all of them the omission will usually be sufficient to discount the narrative.


The narrative should clearly make out the necessary factual elements needed to fit the legal requirements for the desired outcome. Thus, a self-defence case should describe the specific events that fit into the necessary legal tests for self-defence. Similarly, an identification case, from the defence, should provide narrative on the observations not made.



The theory of the case should present a story that has emotional appeal. It should focus on the key witness, usually the client, who should be the protagonist of the story.

Facts Beyond Dispute


A proper theory of the case must be able to explain and accommodate all the facts beyond dispute (FBD).

The FBD of a case are all facts of a case that are most likely to be found by the judge.

FBD can be good, bad, or neutral to your position. The theory must be consistent and explain all the bad FBD. If they are mostly bad then the only available outcome may be a conviction for a lesser charge. Or in the worst case, the only available outcome is a conviction.

Themes of the Case


A theme of a case is a concise summary of the case into a single phrase or sentence. It should capture not only the factual goal of the case but also the emotional ideas behind the case.

In practical terms the theme of a case is much like a tag-line for a movie or a slogan for a product. It captures the theory and it memorable.

A good theme can be a phrase that will be incorporated into the questioning so that the themes can be used in the closing to greater effect.


  • Credibility case (either side): "The truth changed", "the facts changed", "he's changed his mind", "we have his word on that"
  • Fraud case (crown): "by signing he gave a promise", "he gave his word"
  • Self-Defence case (defence): "he didn't/wouldn't stop", "he kept coming"

Defence Themes


In developing a theory for the defence will typically focus on one or more of a number of angles. This will include the more general theme of "jumping to conclusions". The police may have decided who the guilty party was too early on in their investigations, a witness may have presumed the accused was the guilty party based on limited information or common assumptions.

Another angle consists of a more legalistic theory based on the absence of evidence to establish guilt. The theme focuses on what is not known. It discourages the trier of fact from making inferences, encourages doubt about occurrences, and will sometimes suggest speculation on alternate possibilities.

A typically more compelling but riskier variation both of these approaches is to suggest a third-party who is responsible. This is difficult since it often hard to find concrete evidence and will lead to speculation, and further evidentiary rules may allow for the prosecution to rebut the suggestion of a third-party to bolster their position after closing their case.

Incomplete Investigations


Look at the police investigation is a frequent source of theories, most of which arise from either incomplete, sloppy, or even malicious investigations.

A proper investigation is one that is complete. That is to say, all reasonably available sources of evidence have been investigated. This is a function of both the seriousness of the offence and the amount of police resources available.

Investigations can fall short in a number of fashions:

  • failure to make observations:
    • of any injuries upon the accused, in an offence of violence
    • of any other persons in the vicinity as potential witnesses
  • available witnesses known to police were not interviewed
  • failure to take photographs where reasonably useful to the case:
    • at the scene of the incident: this is particularly relevant where the surrounding will help tell what happened such as where a struggle happened.
    • of the injuries observed on the alleged victim
    • of the injuries observed on the accused

Each of these failings individually or in combination may amount to a valid suggestion that the police failed to complete their investigation properly and so did not obtain relevant evidence that may support the defence version of events.