England's clubs must release their players for the 5 November Test against New Zealand, the High Court has ruled.
The decision means the Rugby Football Union (RFU) has won the case brought by Premier Rugby Limited (PRL), which represents England's top clubs.
The decision was based on a strict interpretation of the 2001 Long-Form Agreement between PRL and the RFU.
It means England will play four Tests in November, although PRL is thinking about appealing against the decision.
The RFU won the case because the judge overseeing it, Judge Mackie, said a clause requiring clubs to make players available for "all England representative games" should be given its ordinary and natural meaning.
Mackie rejected PRL's argument that the clause was qualified by another provision restricting the number of release periods for each player to three November internationals and five matches in the RBS Six Nations.
RFU chief executive Francis Baron welcomed the decision but criticised PRL for seeking a ruling from the High Court.
He said: "While we are pleased that the Court has upheld our interpretation of the Long-Form Agreement, we remain disappointed that Premier Rugby chose not to settle this matter through common sense negotiation.
"I'm sure that the game will welcome this result and look forward to joining in the planned celebration event on 5 November."
The case is the latest round in an on-going battle between the two sides for control of England's elite players.
The 5 November international has been arranged by the RFU to mark the opening of the new South Stand at Twickenham.
There is a full round of Premiership fixtures scheduled for the same weekend and the clubs are angry about losing their star attractions.
PRL said in a statement: "We will consider seeking leave to appeal.
"The clubs must now carefully assess the ramifications of this potentially reduced protection from international release and the impact this may have on clubs in the future."
Judge Mackie has urged the two sides to reach an agreement in order to avoid further litigation.
However, with both parties so entrenched and with further complex issues still to be resolved, it is possible the High Court's commercial division has not seen the last of the matter.
The verdict has big implications for England coach Andy Robinson, with the RFU having promised that no-one will have to play in all four internationals.
With the struggling world champions facing Argentina and then two matches against South Africa after the New Zealand game, that severely restricts Robinson with the World Cup by then less than a year away.