Christie took action on Friday, saying he wants to have the state Attorney General's Office study the issue of overdose reporting for the next 18 months before deciding how to proceed.
The bill easily passed both chambers of the Legislature earlier this year. The stated intent was to remove impediments for people who use drugs to report overdoses of others.
In his statement, Christie says giving immunity is not the answer. He says drug prevention and treatment programs could help reduce the number of overdoses.
Democratic Assemblywoman Connie Wagner, who sponsored the bill, says Christie "chose to ignore the reality of the situation" with the veto.