They're really separate issues. Pre-clearance involves U.S. officials being on the Canadian side of the border. There's e-manifest going in both directions. Currently, e-manifest going into the United States is already being implemented. It involves transmitting data in advance to U.S. customs authorities relating to the driver, the carrier, and the vehicle. But I don't think that addresses U.S. concerns about being able to apprehend someone on the Canadian side of the border.
I'm sorry, maybe I don't understand the question.