A New York state judge has reinstated tax shelter claims against law firm Sidley Austin and German banking giant HypoVereinsbank (HVB) on the grounds that a federal deferred prosecution agreement signed by HVB in February presented new evidence of a conspiracy.

Investor E. Roger Williams filed suit last year against Sidley Austin and former partner Raymond J. Ruble, as well as several other defendants. Williams alleged they schemed to induce him to participate in a tax shelter subsequently declared illegal by the Internal Revenue Service.