Former champion Williams joined McLaren on Wednesday in dropping plans to appeal a stewards decision against Formula One rival Racing Point.
The matter will still go to the governing FIA's International Court of Appeal after Ferrari and Renault confirmed their intention to take the matter forward.
The FIA confirmed Racing Point, which argue it has done nothing wrong, was also appealing.
“After careful consideration, Williams have elected not to proceed with the formal appeal,” the Mercedes-powered team said in a statement.
“We believe the FIAs decision to seek the prohibition of extensive car copying for 2021 onwards addresses our most fundamental concern and reasserts the role and responsibility of a constructor within the sport.”
McLaren, which will switch from Renault to Mercedes engines next season, said on Tuesday it had dropped plans to appeal.
Racing Point's car is a visual copy of last year's Mercedes, which provide its engines and gearbox, and the argument is about what it means to be a constructor and how much of the car has to be designed in-house.
It was fined 400,000 euros ($470,000) and docked 15 constructors' championship points after Renault protested the brake ducts on the car. The team are allowed to continue racing with it, however.
- Punjab’s sports policy unparalleled in the country, says Sports Minister Gurmeet Singh Meet Hayer
- Uday Saharan wins Emerging Hero award at the Sportstar ‘Focus Punjab’ Conclave
- Brigadier Harcharan Singh honoured with Sportstar Hero Unsung Champion award at ‘Focus Punjab’ Sports Conclave
- San Diego Open: Vekic, Yastremska advance to second round
- WPL 2024: Struggling UP Warriorz eyes comeback against dominant Mumbai Indians