An immigration judge has ruled that the president of Wisconsin’s largest mosque can be deported under a controversial, cold-war era law the Trump administration has sought to wield against foreign nationals who have been outspoken about Palestinian rights.

Salah Sarsour, a US permanent resident for nearly three decades, was detained by US Immigration and Customs Enforcement in March. He was released after a federal judge found he had probably been detained in retaliation of his advocacy for Palestinian rights, which the federal judge said would render his detention unlawful.

Despite that ruling, the administration pressed forward and fast-tracked Sarsour’s immigration case – a separate legal track – and on Tuesday night an immigration judge ruled he is “removable”.

Judge Jayme Salinardi, who was brought in from out of state to oversee the case, announced he would be retiring shortly after issuing the decision.

In a statement, Sarsour’s attorneys called the ruling “a setback for free speech rights”.

“The case we presented compels only one conclusion, which is that Salah is not deportable, he has done nothing wrong,” Patrick Taurel, one of Sarsour’s attorneys, said during a press conference shortly after the hearing. “He should be given back his green card with an apology for what’s been done to him.”

The Department of Homeland Security did not immediately respond to a request for comment, but claimed before that Sarsour was “suspected of funding terror organizations and lying on immigration forms”. He has denied both claims.

In a statement issued shortly after his arrest, the DHS cited Sarsour’s decades-old military court convictions in Israel for, it said, “throwing a Molotov cocktail at the homes of Israeli armed forces and illegally attempting to possess weapons and ammunition”.

Sarsour said those accusations stemmed from an arrest as a teenager by Israeli soldiers in 1989, during the first intifada. He also says he was forced, under torture and threat of rape, to sign documents in Hebrew without understanding them.

He ultimately spent two years in an Israeli prison after being convicted in a military court system that has a conviction rate of over 96% for Palestinians. Sarsour was again detained by Israeli authorities for nearly three months when he last visited Palestine in 1995.

His lawyers detailed those facts over four immigration court hearings, during which they noted that the government had for years known about Sarsour’s arrests in Israel.

In addition to his involvement with several local organizations, Sarsour is a board member of American Muslims for Palestine (AMP), a national advocacy group that Trump administration officials have accused of countering US foreign policy interests.

“They’re retaliating against him for speaking out about Palestinian human rights,” said Luna Droubi, another attorney. “That should terrify all of us.”

“It’s a principle of this country that people should feel that they can speak freely, and that’s being eradicated”.

In a statement, Sarsour, who has six children and nine grandchildren, all US citizens, called the decision “deeply disappointing” but vowed to “continue fighting”.

“We have a mission: let’s continue to make our voice clear, to protect the first amendment, to support justice,” he told the Guardian in July. “I’ll continue with that message whether I’m inside or outside.”