n a recent Idaho Supreme Court opinion, State v. Fuller, the Court further clarified the law of the fog line in Idaho. You know a fog line is that line on the right side of the right-hand lane of travel. You might think one wheel traveling all the way over the fog line would be enough to justify a traffic stop for failure to maintain your lane. Well, at least in Idaho, you'd be wrong.
In Fuller, the high court looked to prior case law, namely State v. Neil, to make the call. In Neil, the Supreme Court said just having a tire “touch” the fog line wasn't enough to justify a traffic stop based on failure to maintain the lane of travel. In Fuller, the driver's front right tire crossed completely over the line and Ms. Fuller was stopped for failing to maintain her lane. Contraband was discovered in a subsequent search of the vehicle. (Ms. Fuller didn't have a valid driver's license, which led to the search of the car.)
The Court held the fog line is “not a lane barrier,” which means going over it does not amount to failing to maintain the lane of travel. So, the evidence was properly suppressed by the lower court.
Fog line cases come up surprisingly often, most often in DUI cases. Your lawyer needs to keep up on the law specific to your state.