Use your CellPhone.
Photograph a 
SpeedingCar
or the one that
CutYouOffInTraffic
or the one that 
RanAredLight
--
Be sure the
LicensePlate
is in 
ThePhoto
before you send it to 
TheAuthorities
----
They won't act on a single instance, but 
CarlinsDarts 
will accumulate 
-- 
Hopefully 
TheAuthorities 
will then act