The party's health expert Carola Reimann has called for a joint effort from the SPD and the Christian Democrats (CDU) to push the required law through parliament.
In an interview with weekly newspaper Das Parlament, Reimann said a number of pilot projects had been successful in supplying heroin addicts with diamorphine – keeping them healthy and away from crime.
The law needed to broaden such work would have to reclassify diamorphine as a medicine which could then be paid for by statutory health insurers.
She said it was not going to be a "heroin on prescription" experience, but was about maintaining the up to 2,500 worst addicts in the country under medical supervision.
The CDU is said to be in favour of further pilot programmes, despite model projects having been conducted since 2002.
Reimann said 13 federal states had spoken in favour of extending the projects to their regions.
“I think it is ridiculous to put those affected on yet another trial,” she said, adding that it had been shown that diamorphine therapy works.