The recent outbreak of political frankness when it comes to past marijuana use, while refreshing, is not without consequences. Political leaders who made such admissions, including three provincial premiers, the leaders of two national parties and the mayors of Toronto and London, Ont., may find, as thousands of Canadians have, that honesty may not be the best policy when trying to gain entry to the U.S. If you've ever been arrested for cannabis possession, or even admitted to puffing pot, Uncle Sam does not want you.

There are more than 60 grounds of inadmissibility under the U.S. Immigration and Nationality Act, including admitting to smoking marijuana, a crime of "moral turpitude," says Thomas Schreiber, Chief Customs and Border Protection Officer at Blaine, Wash., in an email exchange with Maclean's. He cites the relevant section: "any alien convicted of, or who admits having committed or who admits committing acts which constitute the essential elements of a violation of . . .any law or regulation of a State, the United States or a foreign country relating to a controlled substance . . . is inadmissible."

That cuts quite a swath. Some 40 per cent of Canadians 15 or older admit to smoking marijuana in their lifetime, says a 2011 Health Canada survey. If a U.S. border agent asks any of those more than 10 million Canadians if they've ever used pot, and they answer honestly, they will be barred. Agents have no room for discretion, says Schreiber. "The law is very clear on matters of admissibility."

Full story: Politicians, pot and problems at the border – Canada – Macleans.ca.