The High Court has struck down the concept of spousal privilege, ruling a woman must answer questions about her husband's questionable business dealings.

Louise Stoddart was forced to front the Australian Crime Commission in April 2009 but kept silent, claiming the right of a married person not to give evidence that would incriminate his or her partner.

The commission had been investigating her husband, Gold Coast accountant Ewan Alisdair James Stoddart, over alleged tax fraud.

But the High Court today declared the spousal privilege did not exist in common law.

It found by a majority that Ms Stoddart was a competent witness and under the Australian Crime Commission Act should have been compelled to give answers.