With the new ban, New Jersey is doing "its part to combat wildlife trafficking and protect national security at the same time," said Assemblyman Raj Mukherji (D., Hudson), a sponsor of the bill.
Federal law already prohibits commercial trade of ivory products, according to Christie's office. But the law does not apply to intrastate trade, Mukherji said. And it excludes certain types of ivory, including ivory more than 100 years old, he said. As a result, he said, traffickers have been disguising newly poached ivory to make it look older.
New Jersey's measure "closes the loopholes in ivory commerce," Mukherji said.
Law enforcement officials say New Jersey's ports have played a role in ivory trafficking.
A recent bust by the U.S. Attorney's Office in Newark of a $4.5 million international smuggling ring began in 2011, when federal officials say an informant sold two rhino horns to a middleman at the Vince Lombardi rest stop on the New Jersey Turnpike.
The ring's organizer, a Chinese business owner, pleaded guilty in December 2013. At the time, Paul Fishman, New Jersey's U.S. attorney, told reporters that wildlife trafficking had reached "unprecedented levels," and that New Jersey's ports made the state a hub for smuggling.
New York City, meanwhile, plays a major role in providing demand. The city is the world's second-largest ivory consumer, Mukherji said.
The New York Legislature this summer passed a bill banning the sale and purchase of ivory products, with certain exceptions. Bans also have been proposed in Vermont and Hawaii, Mukherji said.
Christie's action Tuesday was praised by the Humane Society of the United States, which said in a statement that "New Jersey's leadership shines by setting an example for other states and countries to follow." Christie's office noted that advocates for the ban included the actress Meryl Streep, a New Jersey native.