David Boies, the lawyer representing Ms Giuffre, said the duchess “is somebody we can count on to tell the truth”.
The Prince of Wales – Andrew’s brother – could also be dragged into the case, Mr Boies suggested.
He said there were three reasons the duchess may be called upon.
“One, she is in the US so we have jurisdiction over her,” he told the US news site The Daily Beast.
“Two, she is somebody who obviously, at least for a period of time, was a close associate of Prince Andrew and is in a position to perhaps have seen what he did, and perhaps if not to have seen what he did, to have heard people talk.
“Because of her past association with him, she may very well have important know-ledge, and will certainly have some knowledge.
“Three, she is somebody who we can count on to tell the truth. She checks all three boxes.”
There is, however, no evidence to suggest the duchess was a “close associate” of Prince Andrew or has any information concerning the allegations.
If she were to be called, she would be required by law to co-operate as she is an American citizen and the case has been brought in the US.
“We would likely take one or two depositions of people close to Andrew who would have knowledge of his actions,” Mr Boies said. “That might include his ex-wife. It could possibly be his brother.”
Clarence House declined to comment, but is understood to consider the prospect unlikely.