Brexit could be delayed by months, even as long as two years, after a Supreme Court judge of Britain suggested that "comprehensive" legislation was required to trigger Article 50.
Lady Hale told an audience in Kuala Lumpur that "another question" for the court was "whether it would be enough for a simple act of Parliament to authorise the government to give notice, or whether it would have to be a comprehensive replacement for the 1972 (EEC Accession) Act", Sky News reported on Tuesday.
Sky News reported last week that the government was preparing a short bill to push through both the Commons and the Lords to try to keep its March deadline for triggering Article 50.
Labour has said it would not block such a bill in the House of Commons.
Lady Hale's comments, published on Tuesday, come after a High Court ruling that Prime Minister Theresa May cannot trigger Brexit without putting it to a vote in the House of Commons.
That shows that the Supreme Court could adjudicate not just the validity of the government's appeal against the ruling, but also the precise remedy the Government must offer to the claimants if it loses its appeal.
This means the government could have to pass its Great Repeal Bill before triggering Article 50. The Great Repeal Bill is currently not planned to be introduced until the next session of Parliament after May.
Lady Hale, who will sit as one of the judges hearing the government's appeal, also said unequivocally that the "referendum was not legally binding on Parliament".
This was a reference to the referendum legislation passed last year. She also confirmed that for the first time in its history the Supreme Court will sit with all 11 Justices.
(With IANS inputs)