The phrase "a joint brief" is correct and usable in written English.
It can be used in legal or formal contexts to refer to a document that is prepared collaboratively by multiple parties.
Example: "The attorneys submitted a joint brief to the court outlining their shared arguments."
Alternatives: "a collaborative brief" or "a combined brief".
The phalanx of Silicon Valley colleagues and rivals, including Microsoft, Amazon, Google, Facebook, Yahoo, Cisco and others filed a joint brief in California's central district court.
"The Texas statute is a reasonable means of promoting and protecting marriage -- the union of a man and a woman," the Family Research Council and Focus on the Family told the court in a joint brief.
That prospect has led the players unions of all four major sports, none of which were a party to the American Needle suit, to submit a joint brief disputing the N.F.L.'s logic.
The Times Company, Time Inc. and the Newspaper Association of America put it this way in a joint brief: "The point ETW seems blind to is that the use of Mr. Woods's name or likeness in the context of artistic expression does not imply his endorsement of the art.
The United States Court of Appeals for the Eighth Circuit on Wednesday allowed the filing of a joint brief from Major League Baseball, the N.B.A. and the N.H.L., as well as a similar brief from the United States Anti-Doping Agency, which administers Olympic drug testing.
Earlier this summer, the National Football League, National Basketball Association and Major League Baseball issued a joint brief in support of the NHL's efforts to block Balsillie's bid, arguing that the sale would set a dangerous precedent and encourage cash-strapped owners to circumvent the traditional sales process in favor of the court system.
The ceasefire came after Mr. Mueller and Mr. McLaughlin gave a joint briefing on terrorism to President Bush.
Mr. Giuliani shared a private hug with Senator Hillary Rodham Clinton after a joint briefing on Wednesday with the city's Congressional delegation and City Hall officials.
"Some young people have very clear reasons why they cannot live in the family home," a joint briefing by the charities from earlier this year warned.
Senior AFP and Australian Security Intelligence Organisation (Asio) officials have been repeatedly put forward by the government to attempt to quell uncertainty around the new data retention proposals, and gave a joint briefing to journalists in August.
Mr. Bloomberg, who briefs various city officials on the budget before presenting it to reporters, asked the City Council speaker, Gifford Miller, to forgo his normal private budget briefing and instead sit for a joint briefing with City Comptroller William C. Thompson and Betsy Gotbaum, the public advocate.
