The radar used here can detect the speed of multiple cars simultaneously, meaning your speed AND the speed of the car you passed, the latter being the likely basis for your ticket if that car was going over 55 mph. The WSP also has discretion to ticket you on a subjective basis if the trooper believes your speed is unsafe for the conditions (even if you're going under the speed limit). If there was any sign of snow or ice on the road and you passed someone at 70, that might also be a basis for the ticket.
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