The article is wrong on this point: the fact that he was crossing state lines was not a pretext for the stop.

They actually wanted to add another charge. The cameras helped them find the right opportunity to do that.

If they just picked him up driving around, they would only be able to charge those existing crimes.

By waiting for him to cross state lines, they have a chance to add on another charge.

They already had enough PC for the stop, and they could have searched the car as incident to the arrest at any time.

Unless I'm misreading this is all covered explicitly in the article.

	▲	albedoa 7 hours ago \| parent [-]
		The article claims multiple times that the cops used the interstate travel as a pretext for the search that turned up the marijuana, but in most jurisdictions, the arrest would have allowed them to inventory the car anyway as part of the impound process. Unless this jurisdiction is an outlier, the pretext wasn't needed for the search. As the parent comment says, the cops used the interstate travel as a timing strategy to increase the charges.