1. be sure we're jailing the right person. (there are some Americans out there who think you wouldn't be arrested unless you 'did it.')
Some Americans? In the U.S., the whole law enforcement/justice system seems to have an attitude of "guilty until proven innocent". If you're marginalized in any way, you're really in trouble. (GLBT, poor, non-white, homeless, mentally ill, etc.)
Most Americans think they have the greatest justice system in the world, and have no idea of what the system looks like to the rest of the world. The folks participating in this thread do seem to have an idea, and I give you kudos for that.
Wrongful convictions happen in Canada too. The case that disturbed me most was the Guy Paul Morin case. This poor guy was wrongly convicted of raping and killing a little girl basically because he was the neighborhool wierdo. (He was eventually cleared by DNA evidence.) Police focused on him because he was "eccentric" and "a loner". I wonder how many people end up on American death rows because of that kind of stuff.