A judge in Maryland tossed out the state’s 2021 congressional district map Friday, delivering a win to Republicans who called the map biased towards Democrats.

In a lengthy ruling, Anne Arundel County Senior Judge Lynne Battaglia declared the map “an outlier and a product of extreme gerrymandering,” and instructed the General Assembly to draw up a new plan by March 30. State Attorney General Brian Frosh has not indicated whether or not his office will appeal the ruling to the Maryland Court of Appeals. Gov. Larry Hogan has appointed all but one of the seven judges serving on the state’s highest court.

Today Hogan called the judge’s decision a “monumental victory for every Marylander who cares about protecting our democracy.”

“It puts in plain view the partisan, secretive, and rigged process that led to the legislature’s illegal and unconstitutional maps,” the governor said in a statement. Hogan called on the General Assembly to instead adopt maps crafted by the Citizens Redistricting Commission, which he said were “written with accountability and transparency.”

The ruling marks the first time in the state’s history that a judge has ruled a congressional map unconstitutional. The map, drawn by Democrats in the state’s legislature, was challenged in court by the Republican-aligned group Fair Maps Maryland and national conservative activist group Judicial Watch.

The map could have fetched Democrats the vast majority of Maryland’s eight seats in the House of Representatives and made the one district controlled by a Republican — currently Rep. Andy Harris — much more competitive.

A spokesperson for Fair Maps Maryland celebrated the ruling on Friday.

“To call this a big deal would be the understatement of the century,” spokesperson Doug Mayer said in a statement.