A Maryland judge has struck down new U.S. House district maps drawn by the state General Assembly, ruling it an unconstitutional gerrymander that unfairly favors Democrats.

In a 94-page ruling, Judge Lynne Battaglia ruled in favor of Republican groups, including one backed by Gov. Larry Hogan (R), and voters who said their voices were being shut out. Two lawsuits, condensed into a single case, cited a 1972 amendment to the state constitution that requires compact districts and orders legislators to consider natural boundaries and political subdivisions.

Battaglia ordered the General Assembly to try again to draw new congressional district maps that adhere to the state constitution.

“[P]opular sovereignty is the paramount consideration in a republican, democratic government. The limitation of the undue extension of power by any branch of government must be exercised to ensure that the will of the people is heard, no matter under which political placard those governing reside,” Battaglia wrote. The map legislative Democrats passed "subverts that will of those governed.”

Democrats control supermajorities of both the House of Delegates and the state Senate. They used those majorities to draw new district lines that would have given their party an edge in all eight of the state’s congressional districts, adding thousands of new Democratic voters in Anne Arundel County to an Eastern Shore district currently held by Rep. Andy Harris (R).

The effort to tilt Harris’s seat toward Democrats came a decade after the legislative majority engineered a similar gerrymander that dramatically redrew a district in western Maryland, held by then-Rep. Roscoe Bartlett (R). Bartlett lost his seat in the subsequent election.

But a decade ago, Democrat Martin O’Malley held the governor’s mansion in Annapolis. This year, Hogan holds office. Hogan vetoed the Democratic-passed maps, though his veto was overridden.

Fair Maps Maryland, a group Hogan backs, celebrated the ruling as a major win for the GOP.

“Judge Battaglia’s ruling confirms what we have all known for years — Maryland is ground zero for gerrymandering, our districts and political reality reek of it, and there is abundant proof that it is occurring,” the group said in a statement. “Marylanders have been fighting for free and fair elections for decades and for the first time in our state’s shameful history of gerrymandering, we are at the precipice of ending it.”

Hogan has backed a nonpartisan Citizens Redistricting Commission, which produced its own maps last year. In a statement, Hogan urged the General Assembly to take up those maps.

Democrats appear likely to appeal the ruling, and a final decision is likely to come from the state Court of Appeals, Maryland’s equivalent of a Supreme Court.

The office of Maryland Attorney General Brian Frosh (D), which defended the General Assembly’s maps, has not yet decided whether to appeal Battaglia’s ruling.

Maryland’s map was among one of the more aggressive attempts at gerrymandering in the nation, along with states like Oregon, also controlled by Democrats, and Ohio and Texas, controlled by Republicans.

Republicans lost a suit challenging the Oregon maps, while Democrats have won several rounds before the Ohio Supreme Court. The federal Justice Department is suing Texas over its new maps.

--Updated at 2:12 p.m.