The president of the UK's Supreme Court has warned that its independence cannot be properly guaranteed because of the way it is funded by the government.
In a speech in London, Lord Phillips said the court was dependent on what it could persuade the Ministry of Justice (MoJ) to give "by way of contribution".
He argued that the court's budget should be pre-set and ring fenced.
Justice Secretary Ken Clarke said it was a "storm in a teapot" and "of course" the judiciary was independent.
The Supreme Court was set up in 2009, replacing the Law Lords.
Its aim was to emphasise the separation between Parliament's lawmakers and the judges charged with overseeing legislation.
In his speech on Tuesday - entitled "Judicial Independence" - Lord Phillips said that very independence was threatened by the funding arrangements currently in place.
He talked of a tendency on the part of the MoJ to try to annex the Supreme Court as "an outlying part of its empire".
He also complained that the court's chief executive Jenny Rowe should owe her primary loyalty to him, but some in the MoJ clearly felt she should answer to them.
The MoJ is facing large cuts to its budget and has announced the closure of dozens of county and magistrates' courts.
Last year, Ms Rowe warned that swingeing cuts to the Supreme Court's funds would leave it unable to function.
BBC legal affairs analyst Clive Coleman pointed out that Lord Phillips had quoted Lord Faulkner in his speech, who had previously said it was crucial to ring fence Supreme Court funds so ministers could not touch them.
A Supreme Court spokeswoman said a significant part of the court's funding came from Her Majesty's Court Service, which had so far been unable to pay its contribution, which meant the MoJ had to make up the difference.
"The court would like absolute certainty about funding, ideally through a total budget provided by the consolidated fund, to guarantee the institutional independence of the court," she said.
But Ken Clarke told BBC Radio 4's Today programme: "Of course we have judicial independence, it's at the heart of our freedom in this country.
"The government is bound by the law, it doesn't actually determine judgements of courts. He [Lord Phillips] is completely free of political interference."
He added: "If he gives judgements against the government we obey them, and all judges - particularly the Supreme Court - have to be in that position.
"This does not extend to the pay and conditions of his staff, the management of his building and the ordinary running costs.
"I'm afraid Lord Phillips cannot be in some unique position where the court decides on its own budget and tells the Ministry of Justice and the government what it should be."
During its first 15 months, the Supreme Court has made a series of landmark rulings.
It also cleared the way for MPs to face criminal trials following the expenses scandal.