Some of these border crossing posts drive me nuts!!
The truth of the matter is that the laws for crossing either direction are pretty close to each other.
Canadians with past convictions, even for minor crap, are routinly denied entry when travelling south. Who would of guessed that neither country wants convicted criminals visiting?
Canadians cannot import weapons into the US, with some exceptions for LEOs on official business and hunting. American restrictions on entering the US with a firearm are pretty much identical to those US citizens face when travelling North.
Search and seziure -- you have no right to privacy when crossing in either direction. Part of crossing any international boundry is that the host country has the right to search you, your conveyence and anything in your possesion.
The drugs that belonged to someone not in the vehicle. Sounds like the excuse my kids would come up with. "Not mine, I am holding them for a friend"
Know the rules and be prepared!