WASHINGTON (Reuters) - Protesters will get public sites for demonstrations during Republican Donald Trump’s presidential inauguration, a major federal land agency said on Thursday, after being threatened with a lawsuit from civil rights lawyers who accused it of quashing dissent.

Up to 900,000 people are expected to pack into the U.S. capital for the New York businessman’s Jan. 20 swearing-in to his first political office. Some plan to protest Trump’s more controversial promises, including plans to build a wall along the Mexican border and deport illegal immigrants.

Only three of the more than 30 groups seeking to stage rallies either protesting or celebrating Trump’s election independently of the Trump Presidential Inaugural Committee have received permits to use National Park Service land before, during or after Trump’s inauguration.

The agency said it expected to begin issuing permits for demonstration sites on park land in coming days, an announcement that came a few hours after the Partnership for Civil Justice Fund said it would sue if the permits were not issued by Friday.

“We believe that this is a significant victory for free speech. They are doing this under threat of litigation,” Mara Verheyden-Hilliard, the fund’s executive director, said in a telephone interview.

The Park Service had maintained it was following a procedure in place since 2008 by turning over control of sites, including along the parade route from the Capitol to the White House, to Trump’s Presidential Inaugural Committee.

Agency spokesman Mike Litterst said the Park Service would regain control of permits for the Ellipse, a grassy area south of the White House, from the inaugural committee on Jan. 21.

Litterst said in an email that the agency was working with more than 30 permit applicants and was still receiving requests. The Park Service has been under a court order since 2008 mandating it to guarantee free speech during presidential inaugurations.

Three liberal groups, the ANSWER Coalition, the American Constitution Society and the Black is Back Coalition, have been permitted to hold events near the parade route, but only ANSWER was granted one for Inauguration Day, according to the Park Service permits website.

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Some 3,000 police officers and 7,000 National Guard troops from outside the District will be on hand to help provide security at Trump’s swearing in, Chris Geldart, the District of Columbia’s homeland security director said in a phone interview.

The biggest inauguration protest, the Women’s March on Washington on Jan. 21, will go on regardless of the dispute over protest sites since it will be held on city streets.

At least one protest could come with a cloud of marijuana smoke, as the DCMJ pro-pot lobbying group, which spearheaded the legalization of the drug in Washington D.C. in 2015, plans to distribute 4,200 joints near the inaugural site.

Smoking marijuana along the parade route would violate the laws of both the District of Columbia - which allows it only in private spaces - and the federal government, which bans it outright.