Premier Rugby have responded to criticism of their decision to take legal action in their row with the Rugby Football Union by declaring they have been left with no alternative.
The umbrella organisation for the 12 Guinness Premier-ship clubs claim seeking a solution through the courts to the staging of a fourth England international this autumn is in the "interests of the game".
PRL are locked in a battle with the RFU who have arranged to play New Zealand on November 5 to mark the opening of Twickenham's new South Stand.
The Test falls outside the traditional window for autumn internationals and there is a full Premiership programme scheduled for that weekend.
But Twickenham chiefs, offering to provide compensation, insist England players should be released for the match, prompting PRL to seek legal clarification.
RFU chairman Martyn Thomas blasted the clubs' decision to pursue their position in the courts.
But a statement from Premier Rugby said they were "left with no choice but to seek rapid clarification through the courts".
"The process is in the interests of the game as it provides the quickest and cheapest solution. It can, however, run concurrently with negotiations on the Weston Plan, which has been with the RFU for two months and Premier Rugby has also not dismissed mediation.
"But we recognise it would add to the cost and the scope of the mediation needs to take in wider issues than simply one match."
Thomas, who heads the RFU's negotiating team, said: "The RFU deeply regrets PRL's decision to refute this course of action in favour of court proceedings, the intention of which is to frustrate the celebration event to mark the completed bowl and prevent the RFU raising between #3 million and #5 million to partly fund this exciting development. This cannot be in the best interests of the game."