The Led Zeppelin classic "Stairway To Heaven" has been the focus of copyright infringement claims since July 2014, forcing the band later that year to confront claims they stole its biggest hit from Randy Craig Wolfe, founding member of the band Spirit.

In May 2015, surviving Led Zeppelin stars Jimmy Page, Robert Plant and John Paul Jones filed a response to the lawsuit claiming that “Stairway To Heaven” was stolen from an obscure song by the band Spirit. In the paperwork, Page, Plant and Jones admit to having played a concert with Spirit, and to using part of the Spirit song “Fresh Garbage” in a medley they performed during some concerts in 1968 and 1969. Led Zeppelin “deny each and every allegation" in the lawsuit. The band is being sued by Michael Skidmore, the trustee for trust of Spirit frontman Randy Craig Wolfe, who performed under the name Randy California and died in 1997.

The Wrap is now reporting that in the latest turn in the “Stairway to Heaven” copyright saga, the group was accused of undertaking a “pure fishing expedition” in legal papers filed Tuesday (January 12th).

In the filing, attorneys for plaintiff Michael Skidmore — trustee for the Randy Craig Wolfe Trust which, according to the papers, owns Wolfe’s copyrights — blast Team Zeppelin for questioning the validity of the trust.

“There is no evidence to cast even the slightest bit of shade on the validity of the Trust, nor have Defendants argued that there is any real reason to doubt the validity of the Trust,” the papers read. “This is a pure fishing expedition.”

Led Zeppelin’s camp contends that the Wolfe trust is only valid if it is a qualified charitable foundation or other qualified entity, and claims that Skidmore’s legal team hasn’t provided evidence to that effect. Zeppelin’s lawyers are asking Skidmore’s team to provide proof, such as “all Internal Revenue Service notices or correspondence qualifying the Randy Craig Wolfe Trust as a charitable foundation or other qualified entity.”

Read the complete report here.