More than 200 musicians have joined Robin Thicke and Pharrell Williams in appealing a landmark court verdict that found that their hit "Blurred Lines" stole from Marvin Gaye.

Williams, a leading songwriter, and "Blurred Lines" lead singer Thicke were ordered in March 2015 to pay $7.4 million to the estate of soul legend Gaye after a jury found that they plagiarized his song "Got to Give It Up."

The judgment, later reduced to $5.3 million, sent shockwaves through the songwriting community, which has been accustomed to lawsuits alleging musical similarities but never expected courts to take such claims seriously.

In a letter of support for the artists' appeal, 212 musicians who said they had no direct benefit from the ruling voiced alarm at the precedent that was being set.

The signatories include Belinda Carlisle and fellow members of pop group The Go-Go's, John Oates of chart-topping duo Hall & Oates, Rich Robinson of blues rockers The Black Crowes, Curt Smith of New Wave greats Tears for Fears and members of hard rock groups Great White and Poison.

The artists said they were "concerned about the potential adverse impact on their own creativity, on the creativity of future artists and on the music industry in general, if the judgment in this case is allowed to stand."

By eliminating any meaningful standard for drawing the line between permissible inspiration and unlawful copying, the judgment is certain to stifle creativity and impede the creative process," they said in a court filing.

In what was probably an unintentional allusion to the lyrics of "Blurred Lines," the artists said that the law "should provide clearer rules so that songwriters can know when the line is crossed, or at least where the line is."

Since the "Blurred Lines" verdict, a growing number of prominent artists including Led Zeppelin and Ed Sheeran have faced copyright lawsuits.

The jury agreed with Gaye's family that the bass line and sounds of a party atmosphere in "Blurred Lines," the top-selling song in the United States in 2013, unjustly imitated 1977's "Got to Give It Up."

Ed McPherson, a lawyer who submitted the artists' letter, said Gaye's family would have a chance to present its own evidence within the next three weeks.

Formal arguments for the appeal case are not expected to take place until a year from now, he said Wednesday.