This might be a stupid question - but any help is appreciated.

Looking to take a flight from the US to Europe that will take myself and a friend through Toronto early next year, with a plane change in Toronto.

My friend had a bit of trouble 7 years ago and has a felony record. It's been 7 years and she's been law abiding since then - no problems, she was never placed on probation, only served 10 months. Is there going to be any trouble for her to enter Canada for a flight change as we'll only be in the country for about 6 hours and not even leaving the airport ?

I've tried to do some research on this but there's alot of conflicting and confusing info out there on the internet....