SEATTLE – The city of Seattle wants to join a lawsuit to challenge a King County initiative that would ban safe injection sites for drug users.

In court documents filed Friday, Seattle asked a King County judge to allow it to intervene in the lawsuit filed by a group called Protect Public Health. The group sued in August seeking to invalidate Initiative 27 before it goes before voters, arguing that public health policy is beyond the scope of the initiative process.

I-27 would ban supervised sites where people can use heroin and other drugs.

King County is considering two sites as part of a three-year pilot program – one in Seattle and the other outside the city. The city says it has a significant interest in seeing that the overall plan be implemented in full.

Seattle City Attorney Pete Holmes said in a statement Friday that the city needs to intervene to protect the city’s autonomy.