Foreign laws versus Customs and Border Protection
I have had an encrypted laptop searched when re-entering Canada by customs agents... except they absolutely searched the data on the machine. In answer to my courteous and respectful questions as to the purpose of the search request, I was informed that it was for illegal content such as child pornography.
I chose to allow the search and unlocked my device... I did so as it was an agent of my own Government, and I felt comfortable that the corporate data was not at risk.
I questioned my company's lawyer who basically said that I has 2 choices - allow them to search it, or they could seize the laptop and potentially (unlikely) refuse me re-entry in to Canada. When re-entering a country, you are not YET under normal laws and protection against search and seizure.
But, a regular "security" agent or law enforcement, for that matter, in Canada would not be able to seize and search a computer without cause.... and domestic travel is not, to my knowledge, cause to do so.
I will provide advice that I received: if you don't want a foreign official to be able to see it, leave it home. Period.
My $0.02