Check for criminal record when crossing the border into Canada
 

I don't know if this is the right ng to ask about checks on
visitors/temporary residents when they enter Canada via air or land. I have
been interested in this area for a while due to numerous articles about
foreign criminals in Canada. I am aware of the API system now in use by
Immigration and Customs officers when visitors enter Canada on airlines,
etc. It is about time. When visitors cross the border what files are
checked exactly? For example, I assume they are
checking for outstanding warrants, wanted criminals, etc. I suppose they
could also be checking for anyone with a criminal record too but given the
number of people with criminal records just in the U.S. not to mention
elsewhere, I was wondering if this is also automatically checked before
passengers go through Customs? Given the sheer numbers of potential
visitors, is every foreign visitor checked for having a record?

If anyone has any info on this, I would appreciate hearing from you.