#OyVeyDonaldTrump In addition to everything else .... hello Nepotism ....Jared Kushner, Trump’s Son-in-Law, Is Cleared to Serve as Adviser

Jared Kushner arriving for the National Prayer Service at Washington National Cathedral on Saturday.CreditDoug Mills/The New York Times

Hours after President Trump took his oath on Friday, the Justice Department issued an opinion saying that his appointment of his son-in-law, Jared Kushner, as a senior White House adviser would be lawful despite a federal antinepotism law.

In a 14-page opinion signed on Friday, a longtime career lawyer in the Justice Department’s Office of Legal Counsel said that the president’s special hiring authority exempted White House positions from a 1967 law barring the president from employing relatives at a federal agency.

Some legal experts had raised concerns that Mr. Kushner’s appointment violated that law, which Congress enacted several years after President John F. Kennedy had appointed his brother Robert as attorney general.

But the new Justice Department opinion, signed by Daniel L. Koffsky, a deputy assistant attorney general in the legal counsel office, said Mr. Trump had the power to appoint Mr. Kushner anyway because of a subsequent 1978 law that gives the president the authority to appoint White House staff members without regard to other laws restricting employment and compensation of federal employees.

Mr. Koffsky’s opinion acknowledged that in several cases since 1978, the Office of Legal Counsel had determined that the antinepotism statute prevented presidents from appointing relatives to positions.

The revised position came after an effort by Jamie S. Gorelick, Mr. Kushner’s lawyer and a deputy attorney general during the Clinton administration who is now a lawyer at the firm WilmerHale, to clear away obstacles to Mr. Kushner’s appointment.

The opinion paves the way for Mr. Kushner, 35, to join Mr. Trump in the West Wing. Among the new president’s closest advisers during the campaign, Mr. Kushner married Mr. Trump’s daughter Ivanka in 2009. He has run his family’s vast real estate company and has owned a newspaper, The New York Observer.

Mr. Trump announced on Jan. 9 that he would appoint Mr. Kushner, who will not accept a salary. His purview is expected to include the Middle East and Israel, government partnerships with the private sector and matters involving free trade.

“If you can’t produce peace in the Middle East, nobody can,” Mr. Trump said to Mr. Kushner at an event on Thursday.

The appointment of Mr. Kushner will be a dramatic change. In 1977, for example, the Justice Department barred President Jimmy Carter from appointing his son to an unpaid White House role, citing the antinepotism law.

Even after Congress enacted the 1978 law, the Justice Department continued to block proposed appointments of presidential relatives. Mr. Koffsky’s opinion, which he worked on in the final days of the Obama administration, acknowledged a 1983 case in which the office barred President Ronald Reagan from appointing a relative to an advisory committee, and a 2009 case in which it blocked President Barack Obama from appointing his brother-in-law and a half sister to advisory committees.

But, Mr. Koffsky maintained, those opinions failed to adequately address the impact of the special hiring authority that Congress gave the president for his personal staff as part of the 1978 law.

He also wrote that it was unlikely that Congress could bar a president from obtaining informal, ad hoc policy advice from a relative, and a major consequence of allowing Mr. Kushner’s appointment to a formal role is that he will be subject to the usual ethics rules for White House employees, like conflict-of-interest laws.

Mr. Kushner intends to sell some assets to his brother and to put others into a trust overseen by his mother, said Ms. Gorelick, who has worked on the plan. Ms. Gorelick said she had been consulting with federal ethics officials to try to address any conflict-of-interest issues associated with Mr. Kushner’s appointment.

He will also be required to file a financial disclosure report that details his assets and income, and to divest some holdings that could create a conflict of interest.

When Mr. Trump announced Mr. Kushner’s appointment, Ms. Gorelick told reporters that while there were arguments on both sides of the legal question, she believed the “better argument” was that it would be lawful. She also disclosed then that the Trump transition team would seek an Office of Legal Counsel opinion.

In an email on Saturday, Ms. Gorelick said that “we believed that we had the better argument on this,” adding that “the Office of Legal Counsel of the Justice Department — in an opinion by a highly regarded career deputy assistant attorney general — adopted a position consistent with our own.”

Richard W. Painter, who served as a White House lawyer in the George W. Bush administration, said that while he had some doubts about the new opinion, “it is a reasonable interpretation” of the law. “But what is important now,” he added, “is that Mr. Kushner complies with the conflict-of-interest and disclosure provisions, and I wish his father-in-law, the president, would do the same.”