William Pedersen, a reader from St. Peter, Minn., recently shared an interesting tale of his bus trip to Canada's Maritime Provinces. At customs on the Maine border, two fellow travelers faced extended questioning.

"After about an hour, the word came out that the couple being questioned would not be able to enter Canada."

Why? The man had been charged years earlier with driving under the influence of alcohol.

Anyone traveling to Canada should know that your past can follow you to the border — and keep you from crossing it.

The State Department website, travel.state.gov, notes that "anyone with a criminal record (including misdemeanors or alcohol-related driving offenses) may not be able to enter Canada without first obtaining an approval for rehabilitation well in advance of any planned travel."

Travelers with marred records need to apply for this "rehabilitation," which means, according to the Canadian government, that the person in question leads a stable life and shuns criminal activity.

As with so much red tape, it begins with a form. This one asks for employment history and addresses from the age of 18. It also requires a written statement: "Provide reasons why you consider yourself to be rehabilitated and why you do not represent a risk to public safety." The application fee is $200 (Canadian) and can take up to a year to process.

Travelers may be able to get a temporary permit for one visit without having to pay the hefty fee, provided they served no jail time and have committed no other acts that would prevent entry into Canada.

For more information and forms, go to cic.gc.ca/english.

At the U.S.-Canada border, by the way, it isn't exactly an eye for an eye, a DUI for a DUI. According to the U.S. Customs and Border Control website, "A single DUI conviction is not grounds to deny entry into the U.S." But for Canadians with multiple convictions, it's "keep out," unless you get a waiver.

Send your questions or tips to Travel Editor Kerri Westenberg at travel@startribune.com, and follow her on Twitter: @kerriwestenberg.