In a significant development from Washington, a federal judge has mandated that President Donald Trump halt the deployment of National Guard troops in the nation’s capital. This ruling, however, is not expected to be the final chapter in the ongoing legal and political skirmish involving the courts, the president, and local authorities over federal jurisdiction in the district.

U.S. District Judge Jia Cobb issued a temporary stay on her order for 21 days, granting the Trump administration the opportunity to either withdraw the troops or challenge the decision. This move represents a new point of contention in the protracted legal struggle surrounding the use of military troops to assist law enforcement efforts on American soil.

In August, President Trump declared a state of emergency in Washington, federalizing the local police force and deploying National Guard units from eight states as well as the District of Columbia. Although this emergency order expired after a month, the troops remained in place.

The National Guard personnel have been actively involved in patrolling Washington D.C.’s neighborhoods, landmarks, train stations, and busy streets. They have established checkpoints on major highways and have aided federal agents in conducting raids that resulted in numerous arrests, primarily related to immigration violations. Additionally, the troops have engaged in various civic duties such as trash collection and security at sporting events, conventions, and concerts, often interacting with the public by taking selfies with tourists and locals.

The White House has defended the legality of President Trump’s decision to deploy the troops and has committed to appealing the judge’s ruling.

Here’s what to know about the National Guard deployment in the nation’s capital.

The judge ruled the deployment was unlawful

District of Columbia Attorney General Brian Schwalb filed the lawsuit against the administration that led to Cobb’s ruling.

Cobb ruled that Trump’s troop deployment violated the governance of the capital for a variety of reasons, including that the president had taken powers that officially resided in Congress; that the federal district’s autonomy from other states had been violated; and that Trump had moved to make the troop deployment a possibly permanent fixture of the city.

“At its core, Congress has given the District rights to govern itself. Those rights are infringed upon when defendants approve, in excess of their statutory authority, the deployment of National Guard troops to the District,” Cobb wrote.

The judge also added that D.C. “suffers a distinct injury from the presence of out-of-state National Guard units” because “the Constitution placed the District exclusively under Congress’s authority to prevent individual states from exerting any influence over the nation’s capital.”

Cobb added that repeated extensions of the troop deployment by the National Guard into next year “could be read to suggest that the use of the (D.C. National Guard) for crime deterrence and public safety missions in the District may become longstanding, if not permanent.”

Troops won’t necessarily leave the capital following the ruling

The Trump administration has three weeks to appeal the decision and White House officials have already vowed to oppose it. Troops remained stationed around the city on Friday after the ruling came down.

Deployments in Los Angeles, Portland, Oregon and Chicago have each faced court challenges with divergent rulings. The administration has had to scale back its operations in Chicago and Portland while it appeals in both cases.

The White House stands by the deployment

The White House says the Guard’s presence in the capital is a central part of what it calls successful crime-fighting efforts. It dismissed the ruling as wrongly decided.

“President Trump is well within his lawful authority to deploy the National Guard in Washington, D.C., to protect federal assets and assist law enforcement with specific tasks,” said White House spokeswoman Abigail Jackson. “This lawsuit is nothing more than another attempt — at the detriment of DC residents — to undermine the President’s highly successful operations to stop violent crime in DC.”

That stands in contrast to what local D.C. leaders say.

Schwalb, the District’s attorney general, praised the judge’s decision and argued that the arrangement the president had sought for the city would weaken democratic principles.

“From the beginning, we made clear that the U.S. military should not be policing American citizens on American soil,” Schwalb said in a statement. “Normalizing the use of military troops for domestic law enforcement sets a dangerous precedent, where the President can disregard states’ independence and deploy troops wherever and whenever he wants, with no check on his military power.”

D.C. Mayor Muriel Bowser, who has tried to strike a balance between working with some federal authorities and the opposition of some of her voters, has not publicly commented about the ruling.

States across the country have watched D.C.’s legal case play out

The case could have legal implications for Trump’s deployment of National Guard troops to other cities across the country. Dozens of states had joined the case, with their support for each side split along party lines.

The District of Columbia has always had a unique relationship with the federal government. But the legal dispute in D.C. raises some similar questions over the president’s power to deploy troops to aid in domestic law enforcement activities and whether the National Guard can be mobilized indefinitely without the consent of local leaders.

Prior to the D.C. deployment, Trump in June mobilized National Guard troops in Los Angeles as some in the city protested against immigration enforcement activities. Since deploying troops to Washington, Trump has also dispatched National Guard troops to Chicago, Portland and Charlotte, with more cities expected to see deployments in the future.

The mostly Democratic governors and mayors who lead the cities and states in the administration’s crosshairs broadly oppose the deployments. Gov. JB Pritzker of Illinois, in a November interview with the AP, warned of the “militarization of our American cities.” Pritzker and other Democratic governors have been among the most intense legal opponents to Trump’s troop deployments and federal agent surges nationwide.

Some Republican leaders have welcomed federal law enforcement intervention into their states and lent state resources and agents.

Yet some of Trump’s allies have expressed concern. Oklahoma Gov. Kevin Stitt, chair of the Republican Governors Association, warned that Trump’s deployment of National Guard troops without a state’s consent “sets a very dangerous precedent.”