The officer is still in the right to stop you and issue a citation for speeding. Again, by your own admittance you were speeding (68 in a 65). And yes 3 mph over the speed limit might be a little knit picky, but consider you were in a construction zone. Most construction zones are usually between 45 - 55 mph. So is it possible you got a break and not charged with 68 in a construction zone reduced speed? You make a decent argument for your case, but that is what court is for. That doesn't mean the officer was acting beyond his powers by stopping you and issuing a ticket.
Also, an officer sitting on the side of the road making sure motorist slow down in a construction zone is not a speed trap. Try working on the side of the interstate sometime while vehicles are flying by you. Not so fun for those workers trying to make your roads better.
You haven't given any evidence to show the officer did something wrong. If you can provide any other facts to the situation I would reconsider. Maybe explain your definition of a speed trap and how the officer trapped you in to driving 68 mph in a construction zone.
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