Dashboard cameras, already hugely popular in Russia, are becoming more common in North America, especially on commercial vehicles. They allow trucking companies to monitor their drivers for safety and potentially avoid paying unwarranted negligence claims in the event of accidents. They’re also legal on both sides of the U.S.-Canada border.

But not, it appears, on the U.S. side of border crossings. While there’s been no public statement on the issue from U.S. Customs and Border Protection (CBP), a number of truckers have recently reported encountering delays and harassment when entering the U.S. with an operational dashcam. Such incidents have prompted freight carriers and industry groups including the Canadian Trucking Alliance and the Ontario Trucking Association to issue warnings to turn off dashcams when crossing the border.

Authority for the apparent ban is believed to come from the U.S. Code of Federal Regulations (CFR), specifically 41 CFR 102-74.420, which deals with “photographs for news, advertising or commercial purposes”. It generally prohibits taking photographs on Federal property without permission from the relevant agency, and it seems that CBP is one agency that has a policy of not granting such permission.

When enforcing the ban, CBP officers have given the rationale that dashcam footage could be used by terrorists interested in studying ports of entry and immigration procedures to plot attacks and learn how to cross the border without arousing suspicion. (Yes, it has been pointed out that dashcam video is unlikely to contain any information that can’t be found on the National Geographic Channel’s Border Wars documentary series; officers were reportedly unmoved.)

In many cases, enforcement hasn’t meant simply asking that the dashcam be turned off. Some drivers have been subjected to verbal abuse and threatened with revocation of their FAST cards. Even when the CBP officer handles things more professionally, being spotted with a working dashcam usually means a secondary inspection and a delay of up to several hours. Drivers are often forced to delete any existing recordings from the dashcam as well.

Word has gotten around among truckers, most of whom now know to turn off their cameras when approaching the U.S. Some have also taken to covering their lenses just to make sure there’s no question about whether or not they’re recording.

Meanwhile, CBP’s Canadian counterpart, the Canada Border Services Agency (CBSA), is a lot more forthcoming and a lot less strict on the issue. Spokeswoman Esme Bailey is unequivocal that dashcams may be operational both when waiting in line to speak to a Border Services Officer (BSO) and during the interview itself. BSOs can’t force a driver to delete dashcam data, although they can take a look at the footage if they want.

Even that probably won’t happen very often: Bailey said that when a BSO searches electronic files, he or she is looking for “child pornography, obscene material and hate propaganda”. In other words, nothing your dashcam is likely to contain, no matter how badly you got lost on your trip to the States.