A trial to determine whether Led Zeppelin plagiarized the Spirit song "Taurus" while writing "Stairway to Heaven" continues to proceed toward its scheduled May 10 start.

As previously reported, Zeppelin attorneys lost their bid to prevent the trial several weeks ago, ending years of legal maneuvering over the case's validity on a number of grounds. The band's legal team has scored a handful of meaningful victories in recent days, however.

Vintage Vinyl News reports that attorneys for the plaintiffs — who are representing the estate of deceased Spirit founder Randy California on behalf of the band's former bassist, Mark Andes — will not be allowed to present non-album versions of "Taurus" while making their case. This ruling has, in turn, disallowed the testimony of experts who'd offered their opinions based on other "Taurus" recordings.

The judge presiding over the case has also forbidden testimony regarding Led Zeppelin's previous entanglements with songwriters who've accused the band of plagiarism, as well as any testimony on the subject of the band members' drug habits during the '60s and '70s. Also off-limits: discussion of Led Zeppelin's wealth.

Whatever's said during the trial, it will likely be without Zeppelin co-founders Jimmy Page or Robert Plant present. Classic Rock Magazine reports that neither artist is likely to appear before the judge, although both have recorded depositions to be presented at the trial. The other surviving Zeppelin member, John Paul Jones, has been excluded from the case.

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