Gravity Knives in New York

Under New York law, a person who possessed a gravity knife can go to jail for up to one year. If that same person has previously been convicted of a crime, then the possession of the knife is a felony offense and depending on what kind of crime he’s been convicted of in the past, he can go to jail for a lot longer than one year. Everyone knows that New York has strict gun laws, so it wouldn’t be a stretch to assume that New York treats all sorts of weapons harshly. It wouldn’t surprise the average person to discover that brass knuckles, expandable batons, and switchblades are illegal. It also probably wouldn’t surprise someone to learn that the “gravity knife” is also illegal. After all, “gravity knife” sounds pretty menacing. But what actually is a gravity knife? A gravity knife defined by statute is a knife that flicks open with the use of centrifugal force and locks into place without the use of a person’s hands. According to a New York Law Journal Article, these knives came into prevalence in the earlier part of the 20th century because paratroopers needed to be able to open a knife with one hand to cut themselves down from a parachute in case their other hand was tied up. They were considered dangerous by the New York legislature because they can be opened and brandished very quickly.


Police officers and prosecutors determine that a knife is a gravity knife when they can flick it open with their hand and by that force alone, it opens the knife and the knife locks into an open position. If you are found to be in possession of that knife, then you will be arrested and charged. However, there are two problems with this.

The first problem is these knives are very prevalent and are sold openly. In fact, they are so prevalent that the foldable knife that you probably bought from Home Depot a few years ago to help you with random tasks around the house may be a gravity knife. Whether it is simply depends on whether you can open it with one hand. So what is the difference between a legal foldable knife that needs two hands to open versus an illegal gravity knife that only needs one hand? How tight the screw is that connects the blade to the handle. If it’s tight, it won’t open by a flick of the wrist. If it’s loose, it’ll open easily. So a knife that is bought and sold legally can quickly turn illegal and the person won’t even know it if that screw wears down or is loosened. The problem with this is a lot of good people who aren’t criminals find themselves arrested for possessing these knives. Particularly construction workers. Unfortunately, the police are completely tone death with regard to these issues. Even more unfortunate is that so are some prosecutors. Fortunately, judges appear to be moving this issue in the right direction. First, the Office of Court Administration has asked the New York legislature to change the law to include a requirement that the possessor had some unlawful intent while possessing the knife. Courts have also been granting motions to dismiss these cases in the interest of justice. Hopefully this trend continues.

The second problem is the knives that commonly fall into the category of “gravity knives” may not technically open with centrifugal force. The legislature clearly wrote that centrifugal force must be used to open the knife. And people have a general idea of what that means. However, there is a dispute as to whether it is centrifugal force that opens the knife. Some experts contend that it’s not centrifugal force that opens these knives, but is actually the force of kinetic energy. They further content that for the knife to open by the use of centrifugal force, the knife would have to be flung in the opposite direction. It doesn’t help that physicists all agree that centrifugal force itself is fictitious in that what looks like a curved force is really just different forces of inertia at play with each other.

In any event, these knives are causing a headache for a lot of people and sometimes you may need a lawyer to help sort some of these out these issues.