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A federal appeals court refused Friday to dismiss federal corruption charges against Sen. Robert Menendez of New Jersey.

A three-judge panel of the Third Circuit Court of Appeals unanimously rejected his claims that his conduct was constitutionally protected official business.

"Members of Congress are not be super-citizens immune from the criminal process," the court said, quoting from a 1973 US Supreme Court decision on a similar issue.

Related: Sen. Robert Menendez Indictment A Blow to Latino Political Influence

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Federal prosecutors last year accused Menendez of using his U.S. Senate office to help a Florida eye doctor and big political donor, Salomon Melgen, who was under investigation over Medicare billing.

U.S. Sen. Bob Menendez speaks during a news conference talking about Superstorm Sandy relief fund, Friday, July 1, 2016, in Hoboken, N.J. Julio Cortez / AP

The indictment said Menendez urged the government to adopt reimbursement policies that would benefit Melgen, to honor a Dominican port security contract with a company in which Melgen was an investor, and to get visas for Melgen's girlfriends.

In return, prosecutors said, Melgen gave thousands in campaign contributions to Menendez and treated him to luxury Dominican vacations and private jet flights.

Related: Former Virginia Governor Robert McDonnell Spared from Prison Sentence

Menendez argued that the Constitution's speech or debate clause doesn't allow members of Congress to be charged with crimes for their official conduct. But the appeals court said that provision only shields actions related to actual legislation.

"The acts alleged in this case were essentially lobbying on behalf of a particular party," the court said, "and thus, under the specific circumstances, are outside the constitutional safe harbor."

Menendez said his meetings with federal officials were to discuss government policy, but the court said "the focal point of the meetings with executive branch officials was Dr. Melgen."

Friday's decision did not address the merits of the charges and noted that there is some evidence in favor of Menendez. But that's for a jury to work out at trial, the court said.

Mendez's attorney, Abbe David Lowell, said he plans to appeal and "if necessary, raise these issues before the U.S. Supreme Court."