Voting-rights advocates in Pennsylvania filed suit on Thursday to nullify the state’s congressional-district map as an unconstitutional partisan gerrymander, joining other court battles over the role of politics in redistricting already being waged in three other states.

It is the latest major legal effort arguing that gerrymanders have become so egregious they are subverting democracy and creating legislative races with predetermined results.

In a tactical twist, however, the Pennsylvania lawsuit was filed in a state court, which means that if the plaintiffs prevail, the ruling would set no precedent for challenges in other states.

The three other lawsuits, in Maryland, North Carolina and Wisconsin, were filed in federal court and argue that the maps of congressional or state legislative districts violate the federal Constitution.