A possible Canadian law that would force people to hand over encryption passwords would be unconstitutional in the U.S. This would violate people's freedoms, particularly the Fifth Amendment since it would likely constitute an illegal search and seizure. There could be an exception if it is deemed a credible threat to national security, but the bar would be set pretty high.
A proposed Canadian law that gives law enforcement the authority to demand encrypted passwords would not be constitutional in the United States. American citizens are afforded privacy protections against unlawful searches and seizures. Americans should not be required to hand over encrypted passwords to law enforcement, because doing so would be unconstitutional.
The United States has laws against self-incrimination. While it is illegal to conceal or destroy evidence of a crime, it is up to law enforcement agencies to prove that a crime has taken place. If the authorities do obtain a search warrant for personal files, it is up to them to access those files.
We have a legal right to privacy. As it were, giving up encryption passwords defaults that right to privacy, and thus violates one of the Bill of Rights. While the necessity of opening up documents is argued, even if the merit was approved, it is not justification enough to legalize forced abandonment of privacy.