The ruling clears the way for the president to participate in a deposition be the end of the year.
Summer Zervos, an Apprentice contestant in 2005, accused Trump of kissing her against her will at his New York office in 2007 and later groping her at a meeting.
If Trump or sexual assault accuser Summer Zervos make false statements, they could face perjury charges.
Summer Zervos, a former contestant on "The Apprentice," is suing President Donald Trump for defamation.
"We're gathering evidence that we believe will prove that the defendant lied when he falsely denigrated Ms. Zervos," her attorney said.
President Donald Trump's history with women could soon be made very public.
A "sitting president is not immune from being sued in federal court for unofficial acts," Manhattan Supreme Court Justice Jennifer Schecter ruled.
Feminist attorney Gloria Allred has so far raised $30,000 of the hundreds of thousands of dollars she says she needs to bring President Donald Trump to court for sexual misconduct.
Jessica Leeds, Samantha Holvey and Rachel Crooks will also speak on NBC.
The president's lawyers have told a judge she lacks the jurisdiction for a defamation lawsuit filed by Summer Zervos against Trump.
In a 2004 interview with Howard Stern, Trump also suggested contestants were picked for their physical appearance.
A court filing Friday in the case involving a former Apprentice contestant said the president's denials were protected by the First Amendment while he was on the campaign trail last year.