Generally speaking, there are three different kinds of speed limits around the country. They can be broken down into basic, presumed, and absolute speed limits. The premise of a ticket based on a violation of a basic speed limit is that a New York driver was traveling at an unsafe speed for the conditions. Often, law enforcement will argue that the posted speed limit on the road is higher than the real limit for safe driving based on weather or road conditions. Rain, snow, or wind could make it more dangerous to drive and reduce the limit in the officer's opinion from 60 mph to 50 mph.
A ticket based on a presumed speed limit can work in the opposite direction. A person who gets a ticket for driving 40 mph in a 30 mph zone might argue that he or she was driving safely given the travel conditions. It may be possible to argue that other traffic was traveling 40 mph, for example, and that it would be more dangerous to drive under the posted limit.
There are a few defenses against speeding tickets for violating the absolute limit, which simply means the person was driving at a speed faster than the posted limit. Defenses might include speeding due to an emergency, challenging law enforcement's determination of the speed or claiming mistaken identity.
In a case where a person is ticketed for speeding, an attorney might be able to argue that the officer's opinion of the safe speed limit was wrong or have the officer describe the factors that went into his or her determination. An attorney who handles traffic violations might review the facts of the case and advocate for reducing or eliminating the associated fines or other penalties.