Britain's most senior judge has urged the government to explain how courts will interpret rulings set by the European Court of Justice after Brexit.
David Neuberger, president of the UK's Supreme Court, said parliament must be "very clear" and judges should not be blamed for misinterpretations.
"If it doesn't express clearly what the judges should do about decisions of the European Court of Justice, then the judges will simply have to do their best. But to blame the judges for, as it were, making the law when parliament has failed to do so would be unfair," he told the BBC this morning.
"If the UK parliament says we should take into account decisions of the ECJ then we will do so. If it says we shouldn't then we won't. Basically we will do what the statute says."
Theresa May has indicated that leaving the ECJ's jurisdiction as part of the withdrawal from the EU is one of her team's red lines, prompting concerns about issues such as the UK's membership of Euratom.
Despite this the government has said the British courts might still take note of ECJ rulings after the country has left the bloc.
Former British Attorney General Dominic Grieve, a vocal Brexit opponent, agreed with Lord Neuberger.
"The legislation for withdrawing us from the EU... leaves very unclear what the relationship subsequently between European Court of Justice decisions and jurisprudence and our own courts should be," he told BBC radio.
"We're incorporating large amounts of European law into our own law to ensure continuity but how is that to be interpreted thereafter?"