The pound fell on Tuesday morning following a decision by Britain's Supreme Court ruling the Government is not required to consult the devolved assemblies before kick starting the Brexit process.
Judges voted eight to three that Parliament must vote on triggering Article 50, but Scottish, Welsh or Northern Irish assemblies will not get to veto the process.
Sterling was trading 0.8% down against the dollar at 1.24 and fell 0.46% versus the euro at 1.16 euro.
David Cheetham, XT market analyst, said: "The pound has come under some selling pressure in the wake of the Supreme Court ruling, largely due to the fact that the Government doesn't have to consult the Scottish, Welsh or Northern Irish assemblies before triggering Article 50.
"The appeal itself was rejected, but it still remains likely that Mrs May will meet her self-imposed deadline of beginning the formal Brexit process by the end of March.
"Sterling has been volatile over the announcement."
Although MPs are expected to vote it through, the ruling adds a further complication to the Brexit process, adding to uncertainty.
Jeremy Corbyn said Labour would not "frustrate the process for invoking Article 50" but will seek to amend the Government's bill.