The Duke and Duchess of Sussex could be questioned as part of a US defamation case brought by Meghan's half-sister.
Samantha Markle is suing Meghan for "defamation and injurious falsehoods" following the couple's interview with Oprah Winfrey in 2021.
A motion brought by Meghan to stop depositions in the civil case from taking place was dismissed by a judge.
A deposition is a formal statement of evidence in the US, required to be given by a witness or a party involved in a legal case.
In the high-profile interview with Oprah Winfrey, the couple discussed their families, royal life and mental health.
The duchess' half-sister claimed, in a filing submitted in March 2022, that Meghan made "demonstrably false and malicious statements" to a worldwide audience.
Documents obtained by PA News agency show the original motion.
The motion says that it "disseminated false and malicious lies" and had subjected Samantha Markle to "humiliation, shame and hatred on a worldwide scale".
'Rags to royalty'
It adds that Meghan had used "the powerful resources of the Royal Family's public relations operation" to spread "lies worldwide" about Samantha Markle and their father Thomas Markle and describes it as a "premediated campaign to destroy their reputation and credibility".
It was done, the motion says, "to preserve and promote the false 'rags to royalty' narrative".
A motion brought by Meghan to stop depositions in the case from taking place was dismissed on Tuesday by Florida judge Charlene Edwards Honeywell.
But the ruling, in court documents published by the Daily Mail, also seems to question some of the case being brought against Meghan.
After a "preliminary peek", the judge says, some of the claims "may be ripe for dismissal".