VANCOUVER — Marijuana activist Marc Emery's battle to avoid going to a U.S. prison got a boost this week in the House of Commons. Three MPs — Libby Davies of the New Democratic Party, Ujjal Dosanjh of the Liberals and Scott Reid of the Conservatives — presented a petition asking Justice Minister Rob Nicholson not to sign extradition papers that would send Mr. Emery south to serve a five-year sentence for selling marijuana seeds online in 2005.