Prominent music biz attorney Allen Grubman made his move against Billy Joel yesterday in New York Supreme Court, moving to dismiss Joel’s $ 90 million fraud and breach of fiduciary litigation against Grubman and his law firm, as anticipated (Daily Variety, Oct. 13).Strongly worded reply to Joel’s Sept. 23 suit calls it “a sham — a contrived and libelous attempt to cause severe injury to a prestigious law firm and to extort a settlement.” It categorically denies the Joel suit’s allegations of conflicts of interest, that the attorneys paid “kickbacks” to Joel’s former manager and that it had any involvement in managing Joel’s financial affairs. Joel’s suit against the attorneys follows a $ 90 million fraud and breach of contract suit filed against his former manager Frank Weber in 1989. The case against Grubman alleges that the law firm secretly aligned itself with Weber against the singer, knowing about Weber’s alleged misconduct as early as 1982 but not informing Joel. Included are other charges of misconduct, malpractice and numerous conflicts of interest. Grubman, Indursky “had nothing to do” with how Joel spent his money, and, “For all the firm knew, Joel was aware of everything Weber said or did on Joel’s behalf,” per the response. The Joel/Grubman case has the potential to rock the music industry, pitting as it does one of its best-selling artists against arguably the most powerful attorney in the biz. Grubman’s clients have included Madonna, Bruce Springsteen, CBS Records, Michael Jackson, Sting and George Michael. The reply, by Grubman, partners Arthur Indursky and Paul Schindler and their law firm, outlines work the firm did for Joel, estimating that in the 7 1/2 years it represented Joel, it made him more than $ 50 million, including $ 20 million in non-returnable advances on record royalties.