The US special counsel investigating Donald Trump obtained a secret search warrant for the ex-president’s Twitter data in January, unsealed records show.
Jack Smith requested “data and records” relating to Mr Trump’s account which may have included unpublished posts.
After initially resisting the warrant, Twitter eventually complied, but missed a court-ordered deadline by three days.
The delay resulted in the company being handed a $350,000 (£275,000) fine for contempt of court.
The existence of the search warrant and the legal fight over it was revealed in court documents unsealed on Wednesday.