Immigration police here in Mexico have started running checkpoints to verify people's paperwork. Only this time they appear to be looking for Americans and Canadians overstaying tourist or temporary resident visas.Certain long-time residents here, who are used to getting away with crossing back from Tijuana every 6 months, etc., are LIVID to find out that the law applies to them. But as they say, when you're used to superiority, equality feels like oppression.