5-Over rule

The unwritten law in the United States that allows motorists to exceed the speed limit by five to ten miles per hour.

On United States Interstate Highways this rule may be increased in effectiveness. In some states ten, fifteen, or even upwards of twenty miles per hour over the speed limit is acceptable due to local police or highway patrol policies and employment status.

In residential areas, suburbs, highly urban areas, or jurisdictions with very strict quotas this rule may not apply.

See Also: Speeding ticket, Law Enforcement

Well, as I recall from the ending days of my Criminology class a few years ago (we were ending the semester and had more or less run out of things to talk about), the reason for that is the calibration of the radar the cops use.

As I recall, the State Cops, at least in Pennsylvania, have their radar guns calibrated to within about 6 MPH, so that's the minimum over-the-limit speed they can get you for. The local cops' radar varies from 7 to 10 MPH.

Also, as a fun fact (again, at least in PA), the radar gun has to have been recalibrated within the last 30 days, or else it's considered unusable for ticketing purposes.

All this info is correct as I remember it; however, if I posted something wrong, tell me.