The question whether it is legal to carry a knife is a common one, and for good reason.
With state, federal, and local laws governing when it is legal to carry a knife, it can be extremely confusing to know when you are in compliance with the law, and when you are in violation.
As a general rule of thumb, federal laws govern where you can carry knives. While state laws govern the type of knife you can legally carry.
State Knife Laws
A few states have explicit knife statutes, while the majority of states simply have a law that makes it illegal to carry a "concealed" or "dangerous" weapon. In states that do have a knife statute, the answer to whether it is legal to carry a knife will generally depend upon the size of the knife.
For example, it is illegal in California to carry a knife with a blade of two or more inches. Meanwhile, in Texas, knife blades cannot be longer than 5.5 inches. In both states, certain types of knives like switchblades are illegal regardless of the length of the blade. In states that do not have explicit knife laws, whether it is legal to carry a knife will depend upon case law and the discretion of police, prosecutors, and judges.
Local Knife Laws
Along with state laws, many cities, counties, and other municipalities will pass their own ordinances for stricter knife laws. For example, the state of New York does not restrict knife blade lengths, though New York City does have a restriction against blades that are 4 or more inches.
Federal Knife Laws
While state and local laws address the types of knives you can carry, federal laws generally just address where you can carry knives. If you've flown recently, you know that the Transportation Security Administration (TSA) bans travelers from carrying knives, razor blades, swords, and utility blades on an airplane.
Domestic air travelers are allowed to pack knives in checked baggage, as long as the knife is sheathed or securely wrapped. International travelers may be subject to different foreign policies concerning the transportation of knives into and out of other countries.
As you can see, there is no easy answer to when it is legal to carry a knife. If you have questions about the knife laws in your jurisdiction or are facing a knife charge, you will want to consult with an attorney.