A 95-year-old accused of complicity in Nazi war crimes during the Second World War has lost his latest appeal of the federal government’s decision to strip him of his citizenship, a development that may pave the way for his removal from Canada.

Observers say that the government of Prime Minister Justin Trudeau must now make a political decision about whether to order the deportation of Helmut Oberlander, whose legal battles to remain in Canada began in the mid-1990s.

Mr. Oberlander hails from a German family and was raised in Soviet-controlled Ukraine before he came to Canada in the 1950s. He has had his citizenship stripped by successive Liberal and Conservative governments over the past 25 years, but has used the courts to appeal and stave off deportation.

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He has admitted to being a teenage interpreter for what Canada’s courts have called a “civilian-killing squad” active in Nazi-occupied Ukraine during the war. But Mr. Oberlander has argued he was a conscript who never took part in any violence.

In his latest appeal launched last year, Mr. Oberlander argued a more technical point. Specifically, he argued that the latest judge could have been potentially biased because he presided over a previous iteration of the long-running case.

The Federal Court of Appeal rejected that line of argument this week. “I would therefore order … that the notice of appeal be removed from the court file and that the file be closed,” Justice Donald Rennie, writing for a unanimous three-judge panel, ruled on Wednesday.

It’s unclear whether Mr. Oberlander will appeal this latest ruling. Jewish groups, who have long been pressing Ottawa to remove Mr. Oberlander, say that his legal fight may be finally finished.

“This is, I believe, the end of the line,” said Bernie Farber, a former head of the Canadian Jewish Congress who has long followed the case.

Mr. Farber said he hopes the Liberal government will now follow through with the deportation of a man who the courts have repeatedly found to be complicit in Nazi-era war crimes.

Court records show that the current federal cabinet signed an order-in-council in June, 2017, where it collectively decided to strip Mr. Oberlander of his citizenship on the Immigration Minister’s advice.

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If court battles relating to that decision are indeed over, it will fall upon the federal immigration and public-safety departments to determine whether and how to remove him.

A spokesman for Immigration Minister Ahmed Hussen said on Thursday that “our government is pleased with the decision by the Federal Court to uphold the revocation of Mr. Oberlander’s citizenship, which concludes more than 20 years of litigation. This decision further supports our mandate to deny safe haven in Canada to war criminals and persons believed to have committed or been complicit in war crimes, crimes against humanity or genocide.”

Mr. Oberlander’s lawyers had no immediate comment. “I need to talk to my client first,” Ronald Poulton said in an e-mail.

During the Second World War, Mr. Oberlander was affiliated with a Nazi-controlled military unit in Ukraine known as Einsatzkommando 10a, or EK 10a.

Past rulings in the matter have said that “the five EK units of Einsatzgruppen D, to which EK 10a belonged, executed 55,000 civilians between June, 1941, and mid-December, 1941, and another 46,000 by April, 1942, and many more there after … By August, 1942, EK 10a had executed so many thousands of Jews that its operational area was declared Judenrein [Jew-free].”

Mr. Oberlander has sworn statements in court saying he was a teenaged conscript “caught between the brutal worlds of Stalin and Hitler.”

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"I was a young boy, living in fear, doing what I was told. I believed I had no choice. I had absolutely no authority and I was the youngest person in the unit," Mr. Oberlander wrote. "While I was with the German armed forces I did not kill or hurt anyone."

Last fall, the Federal Court of Canada ruled that whether Mr. Oberlander took part in any violence was irrelevant. “Given EK 10a’s unique nature, there was no other purpose to interpretation during interrogation other than to fulfill the group’s deadly mandate.”

A spokeswoman for the appellate court said Mr. Oberlander could still seek to have Canada’s top court review this week’s ruling.

“The decision to remove the notice of appeal from the court file and close the file can be appealed to the Supreme Court of Canada within 60 days,” Amélie Lavictoire said in an e-mail.

Mr. Oberlander settled in Canada after the war, where he built a life in Kitchener. Several years ago in an interview, his daughter Irene Rooney pointed out her father’s advanced age and told The Globe and Mail that “it’s enough now – what the government is putting him through is absolutely ridiculous.”