I was denied entry to Canada once because of a speeding ticket that wasn't settled. Use your passport, they do a driver's license check, but unless you are a convicted felon, minor offenses shouldn't show up with a passport search. And don't give them your social security number. I've been back dozens of times with no problem, except the one time a dancer at Club Erotica stole $40 from my front pocket, but I'll leave that story for a later time.