R v Yazelle, 2012 SKCA 91 is a good source for the holding that the offence of attempting to obstruct justice pursuant to s. 139(2) of the Criminal Code is a substantive offence of specific intent. The Court holds:
The Crown does not dispute that obstruction is a specific intent offence. While it had initially submitted that, in this case, the mens rea of the offence of obstruction is manifest upon proof of the actus reus of the offence, the Crown agreed in oral argument that the requisite mens rea requires proof of an intention to obstruct justice, not just an intention to do an act which has the effect of obstructing justice (see: R. v. Beaudry; R. v. Abdullah, 2010 MBCA 79 (CanLII), 2010 MBCA 79, 259 C.C.C. (3d) 193, at paras. 38-39; and R. v. Esau, 2009 SKCA 31 (CanLII), 2009 SKCA 31, 324 Sask. R. 95).