Swiss bank UBS is holding last-ditch talks with the US government in the hope of avoiding disclosing the personal details of 52,000 American account holders.
The US internal revenue service demanded the names of American clients with assets of $14.8bn lodged in the bank to investigate possible tax evasion in the US. The Swiss government has told the bank it would be illegal under Swiss law to reveal clients' personal details.
A federal court in Miami has given time to the two parties to hold discussions out of court after UBS and the US authorities filed a joint petition.
If UBS fails to comply with a court order in the US, it risks the re-opening of a criminal probe into its activities, which was settled in February.
Scores of other international banks are watching nervously as events unfold. Many feel the US is over-reaching its jurisdiction by asking a foreign bank for details of accounts domiciled overseas.
UBS has welcomed the court hiatus for negotiations.