(FORTUNE Magazine) – OVER THE PAST 23 YEARS, Daniel A. Speights is widely believed to have filed, tried, and settled more asbestos property-damage cases than any other attorney in the U.S. Though the suits--brought for building owners who seek reimbursement for the cost of removing asbestos from their properties--get less public attention than personal-injury cases, they, too, can lead to some major-league payouts. Acting as lead counsel for the property-damage claimants in the Johns Manville bankruptcy many years ago, Speights helped win almost $400 million for his clients--a nice payday for the co-leader of a four-lawyer firm in sleepy Hampton, S.C. (pop. 2,795).

But now this Big Daddy of asbestos property-damage claims stands accused of of pushing the envelope in his filing practices. (For more on shenanigans in the long-running asbestos litigation drama, see "The $200 Billion Miscarriage of Justice" at fortune.com.) In August, Speights admitted that of the 2,938 claims he had filed in the bankruptcy of chemical giant W.R. Grace, 61% involved buildings that did not contain any Grace products; he was suing Grace solely on a conspiracy theory, he explained. He even acknowledged filing 400 claims for clients he could not identify. Grace is demanding that his firm, Speights & Runyan, prove its authority to bring 2,937 (or all but one) of the claims.

"There's absolutely no merit to these objections to our authority," said Speights when reached by FORTUNE in mid-October. He referred us to his briefs and transcripts of his in-court arguments for the details of his rebuttals.

The Speights firm has asserted that it represents more than 650 claimants--even though they "have not responded to requests for express authorization"--on the basis of a nationwide class-action complaint that it filed against Grace in a South Carolina state court in 1992. The very substantial hitch in that argument is that the South Carolina court struck Speights's nationwide claims more than a decade ago, finding that South Carolina law barred them. "I believe I not only had the authority," Speights argued at an August hearing, "I was told [by a legal ethics professor] that I had a fiduciary obligation to file claims on behalf of that ... class." He argues that he would have eventually appealed the order striking his out-of-state claims if Grace hadn't first gone bankrupt. On Oct. 21, Speights agreed to withdraw at least 1,400 claims--those relating to properties with no Grace products in them--but he continues to press his class filings.

Speights's scattershot filing practices have not been confined to the Grace bankruptcy. This past March in Federal-Mogul's Chapter 11 proceeding, he voluntarily withdrew 1,228 of 2,915 claims after challenge; in April he pulled 132 of 300 from the U.S. Mineral bankruptcy; and in September 2003 he dropped 328 of 366 claims filed against Owens Corning.

Of course, in the twisted world of asbestos litigation, Speights's behavior makes a certain kind of sense. If your clients are trying to recover their fair share of the limited funds in a bankrupt company's estate, and they're competing with a host of personal-injury claims that may well be spurious, it must be tempting to look for your own competitive advantage--and let the courts sort it out.