I think there are two ways to do it. One is to ensure that front-line officers receive a bare minimum of legal education when it comes to self-defence. Now, we're not expecting police officers.... I've encountered many police officers who are law graduates, who do have law degrees, but the vast majority do not, and you can't burden every police officer with having to carry around the Criminal Reports for the past 100 years.
What you can do, however, is number one, have a change in policy that reflects training in these areas. The second thing to do is remember what police officers do often refer to, and that is the Criminal Code. Very often police officers will open the Criminal Code as a reference point. If these principles are only in the common law, they are equally as binding as if they were in the Criminal Code, but they are just not accessible.
To me, an easy answer to this is to, say, take the common law that already governs the courts—that's why we see so many acquittals, but so many charges as well—and import those into the Criminal Code. Let the police officer say you don't need to weigh the niceties of your actions, or you're entitled to be mistaken. You don't need a law degree to know that. I can just read it in the Criminal Code.