I've been carrying a knife on me for years – I actually feel a little awkward and naked if I'm not carrying. I grew up in a remote rural area where almost everyone, men in particular, carried a knife on a daily basis. My first grade teacher actually taught us that if you went hiking without a knife, you could just as well have left your right hand at home. I believe that a knife is the single most useful tool you can have on you, and I try to teach the kids to respect and appreciate a good blade.“Great knife, small hunter. Small knife, great hunter.”-Sámi saying
As a newcomer to Canada I wanted to find out which laws I needed to know about, so as not to get in trouble with the law and have my knife taken away from me, or worse. Having researched this a fair bit, I have come to a conclusion: Barring a few definitives, what kind of blade, and where you can carry it, it largely comes down to common sense.
Today I actually visited the local police station and asked to talk to an officer about this issue. What I was told was not to carry prohibited knives (see below), and, though not in as many words, to not be a dick, i.e. don't wave it around, and don't threaten to wave it around. Notably, there are (according to the constable and my own research) no laws regulating blade length.
As for the meat on the legal bones, here's what I've found.
Section 91(3) of the Criminal Code  states that possession of a “prohibited weapon” is a criminal offence. Section 84(1) defines a prohibited weapon thus:
“(a) a knife that has a blade that opens automatically by gravity or centrifugal force or by hand pressure applied to a button, spring or other device in or attached to the handle of the knife, or
(b) any weapon, other than a firearm, that is prescribed to be a prohibited weapon.”
In the above, (b) is somewhat vague, but here I've found The Legality of Martial Arts Weapons In Canada, by Q. D. Agnew* to be of great help. Here the following types of knives are listed as being “prohibited”:
“(a) a knife with a retractable or folding blade which, by design or through wear [emphasis added], will open by centrifugal force or gravity, or by a spring or similar device. This has been interpreted by the courts to include a butterfly knife;
(e) a push dagger, namely a knife where the blade is perpendicular to the handle;
(f) any item under 30 cm which looks like another object but which conceals a blade.”
Also when discussing this, it is imperative to keep in mind that section 2 of the Criminal Code defines a weapon as “any thing used, designed to be used or intended for use (a) in causing death or injury to any person, or (b) for the purpose of threatening or intimidating any person.” With this in mind you should never describe the purpose for you carrying as being for self defence, as this will – by intent – classify your knife as a weapon rather than a tool. Also, using the blade of your Leatherman to harm someone, unless it is abundantly clear that you had no other option, will by all likelihood land you in trouble.
There are other sections of the Code that bears noting when carrying a blade in public as well. I would particularly like to point out section 89(1), which states that: “Every person commits an offence who, without lawful excuse, carries a weapon, a prohibited device or any ammunition or prohibited ammunition while the person is attending or is on the way to attend a public meeting.” Thus, to err on the side of caution, if you are attending a public meeting, leave the knife at home or in the car.
One of the more troubling aspects of carrying legally is concealment. S. 90(1) states that: “Every person commits an offence who carries a weapon, a prohibited device or any prohibited ammunition concealed, unless the person is authorized under the Firearms Act to carry it concealed.” This becomes a little prickly when it comes to pocket knives. Is it concealed if it is in fact carried in your pocket? And with looking at what I've discussed above, is a pocket knife a weapon? In the end, most of this seems to be left to the discretion of the individual officer. The problem here is of course that this can easily translate to “the whim of the officer in question.” This has led me to conclude that if you ever get in trouble for carrying, you should make sure to get the name and badge number of the officer, as well as the filing number of the report, and for the confiscated item, if any. Then talk to a lawyer about it.
I would also recommend that you read Q. D. Agnew's The Legality of Martial Arts Weapons In Canada, as it discusses several relevant matters in regards to legal carry.
* Unless my Google-fu betrays me, Q. D. Agnew was appointed to the bench in Saskatoon, SK, in 2009 (after the above mentioned article was published – in 2004) and is therefore to be styled His Honour.
DISCLAIMER: I am not a lawyer, nor do I hold any legal degree or profession in Canada nor any other country. This is not intended as legal advice in any way.