Marte Mjøs Persen, the leader of the Labour party in the city, said that she and her colleagues had been impressed by the success of decriminalization in Portugal, where deaths from overdose have dropped sharply.
"We see that there have been some really good results from this, particularly in Portugal. We do not see the point of forcing heavily dependent users into prison, and would rather replace punishment with rehabilitation," she said.
"The debate around drugs policy has been characterized by too much moralizing and an insufficiently scientific approach," she said.
The party adopted the new policy at a meeting over the weekend.
Bergen, Norway's second largest city, has long faced problems with heroin addiction, with users long buying and using drugs openly in parts of Nygårdsparken in the city centre.
There are few signs, however, that the party's national leadership are behind the new policy, with the party's justice spokesperson Hadi Tajik stressing that she believed in keeping drugs illegal.
Mjøs, however, pointed out that the Bergen party had in the past driven new ideas which later became national party policy.
"We know that Bergen Labor has pushed ahead in a number of cases, and drugs policy is an example of this," she said. "We see that the more we talk about it, the more interested people are. The decision is made on knowledge and science, and I believe that Labour will come with us."
A few weeks ago, the actor and Labour party member Kristoffer Joner proposed decriminalizing marijuana use and possession at the party's annual conference in Stavanger.