The U.S. Customs and Border Protection Agency has begun enforcement on a rule that could have Canadian drivers stopped in their tracks at the border.

As of May 1, all drivers hauling goods into the United States under the BRASS system – which stands for Border Release Advance Screening and Selectivity – must also be members of the Free and Secure Trade program.

Between May 1 and May 15, drivers who try to cross the border using BRASS alone will face a fine of $5,000. On and after May 16, the drivers will be denied entrance into the United States, according to a press release from the agency.

The new requirement, a major component of the Trade Act of 2002, could cause longer waiting lines at FAST enrollment centers; however, the agency indicated it would extend the hours and increase staffing to help alleviate any problems.