COLLEGE PARK, Md. (AP) — A federal judge has thrown out a lawsuit that accused leaders of the Southern Poverty Law Center of trying to financially destroy one of the organizations that it has labeled as a hate group.

The Center for Immigration Studies' lawsuit is devoid of any allegation that the law center made a false statement about the Washington-based nonprofit, U.S. District Judge Amy Berman Jackson in Washington, D.C., said in her ruling Friday.

"The upshot of the complaint is that defendants advanced a conclusion that was debatable, and that this expression of a flawed opinion harmed plaintiff's reputation," Jackson wrote.

The research group accused the Montgomery, Alabama-based law center's leaders of conspiring to violate the Racketeer Influenced and Corrupt Organizations Act when they designated it as a hate group in 2016. The judge, however, said the suit improperly attempts to "shoehorn" a defamation claim into the framework of a RICO case.

The law center's attorneys asked the judge to impose monetary sanctions against the group for filing claims that it said were frivolous and designed to "censor constitutionally protected speech." The law center also argued that the First Amendment barred the suit's claims.

Jackson refused to impose sanctions, concluding the lawsuit wasn't "completely frivolous." The judge also said she didn't need to rule on the law center's First Amendment arguments because she found that the suit failed to state a claim under the RICO statute.

On its website, the law center describes the Center for Immigration Studies as the "go-to think tank for the anti-immigrant movement" and says it has a history of circulating the work of white nationalist and anti-Semitic writers.

The research group says on its website that it has a "pro-immigrant, low-immigration vision which seeks fewer immigrants but a warmer welcome for those admitted."

Mark Krikorian, the group's executive director, said in an email Monday that the group hasn't yet decided whether to appeal.

The law center's interim president, Karen Baynes-Dunning, said the group stands by its listing of CIS as an anti-immigrant hate group.

"As groups like CIS continue to infect the mainstream with their hateful anti-immigrant rhetoric, we will continue to call out their hate and bigotry whenever we see it," she said in a statement.

The law center has tracked far-right extremist groups, including the Ku Klux Klan, for decades. Other organizations have sued over the law center's list of hate groups.

In January 2018, a federal judge in Virginia ruled that the First Amendment protected a charity tracking website's use of the law center's hate group labels.

The founder of the far-right Proud Boys sued the law center in February for labeling the organization as a hate group. That federal case is still pending in Alabama.

In June 2018, the law center apologized to a London-based group, Quilliam, and its founder, Maajid Nawaz, and agreed to pay $3.4 million in an out-of-court settlement after labeling them as anti-Muslim extremists.