Mr Brown has pushed ahead with ratification despite Ireland's rejection of the treaty in a referendum and the clear opposition of British voters.
The judge is considering a case brought by Stuart Wheeler, the millionaire eurosceptic, which alleges that ministers have acted unlawfully by trying to ratify the treaty without a British referendum.
The Government won a final House of Lords vote on a bill ratifying the treaty on Wednesday, and the new law enabling ratification received Royal Assent on Thursday.
In a direction handed down today, Lord Justice Richards expressed surprise that ministers are pressing ahead with ratification even though he has not yet delivered his judgement on Mr Wheeler's case. The judge said: "The court is very surprised that the government apparently proposes to ratify while the claimant's challenge to the decision not to hold a referendum on ratification is before the court." He added: "The court expects judgment to be handed down next week. The defendants are invited to stay their hand voluntarily until judgment."
Although the law allowing UK ratification is now in place, the formal act of ratification which involves the British government depositing legal papers in Rome has not yet taken place.