De Minimus Non Curat Lex
The principle of de minimus non curat lex excludes certain acts from criminal sanctions due to their trivial nature. The principle is based on the premise that the law should not concern itself with trifling matters.
The doctrine should applied to "harmless conduct" perpetrated by someone who has "not really done anything [criminally] wrong". It is conduct "for which there is no reasoned apprehension or harm to any legitimate personal or social interest."
The availability of lower end penalties, such as absolute discharges, for a conviction can be influential on whether the decline to apply the doctrine to some minor offences.
The application of the principle of de minimus non curat lex is a question of law and reviewable on a standard of correctness.
Offences of Violence
There is on a "limited" societal interest in applying 'de minimus to offences of violence.
In general, the least touching of another person without their consent constitutes an assault. The strength of the force is immaterial to consideration of guilt.  However, non-consensual touching amounting to a trivial assault can be subject to a de minimus finding.
"Light strikes" can fall within the meaning of "trifling".
A grab to the arm and pull of a person 10 to 15 meters is not trifling.
The principle cannot generally be applied in the context of domestic violence.
The non-consensual "dancing" with a security staff member is not an assault on the basis of de minimus. 
Pushing of a minister in the chest nearly causing him to trip is not trifling. 
- R. v W.(C.D.) 2016 NSPC 31 (CanLII) at para 22
- see R v Dawydiuk (2010), 253 CCC (3d) 493, 2010 BCCA 162 (CanLII)
- see R v Palombi, 2007 ONCA 486 (CanLII), (2007), 222 CCC (3d) 528 (Ont. C.A.)
R v Juneja, 2009 ONCJ 572 (CanLII)
R v Hinchey, 1996 CanLII 157 (SCC),  3 SCR 1128, (1996) 111 CCC (3d) 353 (SCC) at P 380-81
- R v Merasty, 2002 SKPC 86 (CanLII)
R v Wiebe, 2001 SKQB 389 (CanLII)
- R v Rumo, 2013 ONSC 1856 (CanLII)
- R v Downey, 2002 NSSC 226 (CanLII) at para 38
R v RHL,  NSJ 468 at para 35 (NSCA)
- R v Murphy, 2010 NBPC 40 (CanLII)
- R v Kubassek, 2004 CanLII 7571 (ON CA),  O.J. No. 3483 (C.A) - overturned trial judge acquittal
The defence can be invoked in relation to the possession of drugs where the amounts alleged are merely residual particles of a controlled substance. 
The existence of drug residue can be evidence of past possession.