Post offence conduct (POC) is a form of circumstantial evidence. It is admissible based on relevance. The utility depends on what inferences can be fairly drawn from the circumstances in its entirety. 
The trier of fact must use POC to consider "what a person logically would or might do in given circumstances".
It will generally be admissible in order to establish that "the accused acted in a manner which, based on human experience and logic, is consistent with the conduct of a guilty person and inconsistent with the conduct of an innocent person".
Probative Value of Evidence
The relevance of POC varies. There is "no prefabricated rule [that] stamps certain kinds of after-the-fact conduct as always or never relevant to a particular fact in issue". 
The Judge must decide "on the basis of the evidence as a whole" if the conduct "related to the offence, or something else".
Conduct can be so ambiguous in context that it should be given no probative value at all.
Conduct can be probative to the actus reus but provide no value to the mens rea of the offence.
Examples of Post-Offence Conduct
POC is frequently seen as:
- flight from the scene of the crime or the jurisdiction in which the crime was committed;
- attempts to resist arrest;
- failure to appear at trial; and
- acts of concealment such as lying, assuming a false name, changing one's appearance, and hiding or disposing of evidence.
This inference is case-specific based on factors such as:
- the nature of the conduct;
- the facts sought to be inferred from the conduct;
- the positions of the parties; and
- the totality of the evidence.
Valid Uses of Admissible Post-Offence Conduct
While POC may be probative to culpability, it should not be used to determine the level of that culpability. That is to say, POC should generally not be admissible in order to establish a state of mind of the accused where the actus reus is already admitted. It follows that it should generally not be used to determine the difference between murder and manslaughter. POC can be used to attack credibility.
An exculpatory statement that has been discredited can only be used to make to an adverse inference against the accused where there is independent evidence of fabrication. The key is to establish an intent to deceive to support an inference of consciousness of guilt.
Such statements should be treated in the same manner as alibis.
Proof of the accused's flight from a scene permits an inference that an offence occurred. It does not permit the inference, without more, that it was a specific offence charged.
It can be used to assess the validity of a claim of self-defence.
Where POC occurs once multiple offences committed it is permissible for the jury to determine the weight if any that is placed on the POC with respect to each offence. It is not necessary to give a "no probative value" instructions expected where there is a different explanation possible.
Jury instructions must be cautious not to create circular reasoning whereby evidence is determined to be POC because he was conscious that he committed the offence.
Where innocence and guilt are both reasonable inferences then a "no probative value" instruction may be necessary.
Juries must be cautioned against "drawing incriminating inferences from post-offence conduct without considering alternate explanations for the impugned conduct."
R v Gagnon 2006 MBCA 125 (CanLII)
R v White, 2011 SCC 13 (CanLII),  1 SCR 433 at para 22
- R v White at para 23
- R v Teske, 2005 CanLII 31847 (ON CA),  O.J. No. 3759 (C.A.) at para 85
- R v Hall, 2010 ONCA 724 (CanLII)
R v Angelis, 2013 ONCA 70 (CanLII) at para 51
R v Peavoy, 1997 CanLII 3028 (ON CA), (1997), 34 O.R. (3d) 620 (C.A), at p. 629
- R v Turcotte 2005 SCC 50 (CanLII) at para 37
- R v White, 1998 CanLII 789 (SCC),  2 SCR 72, (1998) 125 CCC (3d) 385
- R v Cudjoe, 2009 ONCA 543 (CanLII) at para 79
R v White, 2011 SCC 13 (CanLII),  1 S.C.R. 433, at paras. 105-6
R v Roy, 2004 CarswellOnt 3937 (Ont. C.A.), at para. 75
R v Nicholson, 2017 ONCA 3 at para 15
Nicholson at para 15
- R v Allen, 2009 ABCA 341 (CanLII) at para 73
Allen, ibid. at para 73
- R v White
R v Parrington, (1985), 20 CCC (3d) 184(*no link)
- R v Ruddick, (1980), 57 CCC (2d) 421, (Ont. C.A.)(*no link)
R v Figueroa (2008), 232 CCC (3d) 51 (Ont. C.A.), 2008 ONCA 106 (CanLII) at paras 33 and 35
Cudjoe, supra, at para 78
Angelis, supra at para 52, 53
R v Jaw, 2009 SCC 42 (CanLII) at para 39
- Angelis, supra at para 53
- Jaw, supra at para 39
- R v Hein 2008 BCCA 109 (CanLII) at para 53
R v Hibbert, 2002 SCC 39 (CanLII) at para 67
R v Tessier 1997 CanLII 3475
- R v O'Connor 2002 CanLII 3540 at para 26-27
- R v Bennett, 2003 CanLII 21292 (ONCA)
- R v Andrade, (1985) 6 OAC 345, 18 CCC (3d) 41(*no link) at 67
- O'Connor, ibid. at para 18
R v Nicholson, 2017 ONCA 3 at para 8
- R v Williams, 2014 ONSC 2808 (CanLII),
- Williams, ibid.
- R v Hall, 2010 ONCA 724 (CanLII), at paras 142 to 144
Kostyk, 2014 ONCA 447 (CanLII), at paras 91 to 95
POC can be used to detemrine intent in limited circumstances. Generally, it is not permitted as the inference of consciousness of guilt is "highly ambiguous and susceptible to ...error."
Where there is a risk of an improper inference of intent, the judge must give a "no probative value" instructions to the jury.
Evidence of flight cannot be used to establish intent for murder as "evidence of flight was equally consistent with the unlawful act offence of manslaughter."
R v White, 2009 BCCA 513 (CanLII) at para 60
An attempt to commit suicide has been given weight as POC suggesting guilt.
Evidence of Intent to Kill
POC constituting statements and acts of the accused can go to evidence of "planning and deliberation" in a homicide case.
POC that includes wrapping the victim in a sheet and leaving them to die in a bathtub as well as fleeing the scene and not calling for medical assistance.
- e.g. R v McNeice, 2013 BCCA 98 (CanLII) - accused charged with child pornography offences left suicide note apologizing to family
R v Smith, 2014 ONCA 324 (CanLII) - accused stated "...I listened to my mind. Eugena is dead" and used victim's facebook account to "de-friend" another person
R v Poitras, 2002 CanLII 23583 (ON CA), (2002), 57 O.R. (3d) 538 (C.A.)
R v Penney,  O.J. No. 5914 (S.C.)(*no link)
- R v McArthur, 2013 SKCA 139 (CanLII) at para 13