The FAA claims and it is written. It is a federal crime to shoot down a drone. as it is considered a legitimate aircraft.
"The FAA considers unmanned aircraft of any size to be covered under
Title 18 of the United States Code 32, which describes “sabotage to include destruction of any aircraft in the special aircraft jurisdiction of the United States.” Violation of this code carries a maximum prison sentence of 20 years. In other words, it’s illegal to shoot down any aircraft in the U.S., including a drone, according to federal law. And lest you decide that simply jamming or intercepting control of the offending drone might be more your style, know that the FCC considers any form of “jamming” or otherwise interfering with radio transmission to be a violation of the
Communications Act of 1934. Between these two federal laws, most anti-drone technology on the market (including net guns and jamming guns) could put you into some legal hot water."