Kushner's appointment was telegraphed over the weekend by a statement from his lawyer that said that Kushner is preparing to resign from his position overseeing his family's real estate empire and to divest "substantial assets" if he takes a role in Trump's White House.
Some ethical experts question whether a Kushner appointment would violate a federal anti-nepotism statute. The 1967 law, which came about after President John F. Kennedy named his brother as attorney general, forbids public officials from hiring family members in agencies or offices they oversee. It explicitly lists sons-in-laws as prohibited employees.
Some lawyers argue that the White House is exempt because it is not considered an agency.
But both Richard Painter and Norman Eisen, who served as chief White House ethics lawyers under Presidents George W. Bush and Barack Obama, respectively, say they counselled their presidents to avoiding appointing relatives to West Wing jobs.
Trump could ask Congress to amend the statute if he wanted to make it explicit that Kushner is free to serve.
The issue was examined but not resolved in a court case in the early 1990s involving Hillary Clinton's leadership of a health care panel.
Kushner has a web of business interests, focused heavily on real estate development.
Though Kushner's company is focused primarily on development in New York and New Jersey, it has often relied on foreign investment, and its earnings could be influenced by Trump administration trade and foreign relations policies.
Kushner's lawyer, WilmerHale partner Jamie Gorelick, said Saturday that Kushner would recuse himself from matters that would have a direct impact on his remaining financial interests and abide by other federal ethics rules.
Trump declined to discuss Kushner's role when talking to reporters Monday morning (Tuesday NZ time).