We all have heard the horror stories of US citizens being denied entry into Canada for DUI's and old minor offences in the past, and the Canadian government has made some changes to make these ridiculous incidences less frequent thanks to a huge lobby from the tourism sectors. Thought I'd pass on this article about how the border can work the other way so you don't think it's just on the Canadian side. Guess both countries have a long way to go to make border crossing regulations reasonable.
Super Bowl Contest Winner Denied Entry to U.S. Because he Smoked Pot in 1981
A Canadian man who beat out four million competitors to win a fantasy football league’s grand prize of tickets to last night’s Super Bowl was stopped at the border and denied entry because U.S. customs officials discovered he had a minor pot possession conviction on his record from 1981.