Maryland Senate President Thomas V. Mike Miller Jr. on July 30, 2018, in the State House in Annapolis. (Marvin Joseph/The Washington Post)

THE SUPREME COURT made one thing very clear last week: Citizens tired of politicians choosing their voters, rather than the other way around, cannot look to federal courts for help ending even extreme gerrymandering. And in Maryland, the district maps are truly extreme.

The state’s congressional map was one of two recently litigated up to the high court on the theory — wrong, it turned out — that it was such an affront to basic democratic principles that the justices could not sit by and pronounce the lines unreviewable. Former Maryland governor Martin O’Malley (D) even admitted in court testimony that Democrats shamelessly drew the state’s legislative map with the goal of squeezing out one last congressional seat. The gambit worked. Maryland’s 6th District flipped, leaving the state with only one Republican lawmaker on Capitol Hill, out of a House delegation of eight.

Following the ruling, Maryland Gov. Larry Hogan (R) said he intends to push redistricting reform through the General Assembly. But Democratic leaders appear to have no more interest in doing so now than they have in past years. “The Supreme Court ruling only strengthens the need for Congress and the President to work together to create a set of rules across the country,” said Senate President Thomas V. Mike Miller Jr. (D-Calvert). In other words: Don’t expect Maryland state lawmakers to do anything about the issue. Though Republicans have generally been the most aggressive gerrymanderers nationally, Democrats have a lock on the Maryland legislature and apparently intend to use it in the 2020 redistricting cycle.

The only defense of this behavior is nakedly partisan: Republicans would do this if they were in Maryland Democrats’ shoes, and they have aggressively gerrymandered in other states. No need for Democrats to unilaterally disarm in states they control. It is just this sort of thinking that will prevent reform in state after state — until enough citizens demand it. A growing number of states, red and blue, have seen recent ballot initiatives and legislative activity around redistricting reform, often in the face of opposition from old-school power brokers such as Mr. Miller. Increasingly, the question is not whether to unilaterally disarm, but whether to add momentum to a movement to clean up U.S. democracy — or, by refusing to do so, helping to hobble it.

Maryland need not look far for inspiration. Virginia’s General Assembly this year passed a plan to create a redistricting commission that would draw up its legislative maps. The plan must pass again next year and face a public vote, as it requires a state constitutional amendment. We hope and expect Virginia will overcome both hurdles. In which case, what would Maryland’s excuse be?