Establishes "MarcAnthony's Law;" criminalizes use of defaced or stolen firearm to injure a police officer; enhances penalties for defacing firearm.

S 2903, "MarcAnthony's Law," creates new criminal penalties for using defaced or stolen firearms to harm police officers in New Jersey. It classifies causing serious injury as a first-degree crime and causing bodily injury as a second-degree crime. The law specifically defines "defacing" a firearm as removing or altering its maker's name, model, or serial number (excluding normal wear and tear), and prohibits convictions from merging with other charges for the same act. This bill directly affects law enforcement officers and individuals who use altered or stolen firearms against them. The legislation amends New Jersey's criminal code to strengthen penalties for this specific offense.