Johnson & Johnson baby powder.

In a major setback for Johnson & Johnson, the first federal judge to rule on the reliability of plaintiffs' experts testifying about whether baby powder causes ovarian cancer has admitted them in potentially more than 16,000 lawsuits.

On Monday, U.S. District Judge Freda Wolfson in New Jersey, who is overseeing the talcum powder multidistrict litigation against Johnson & Johnson, found that five scientific experts for the plaintiffs, two of whom have testified before Congress on talcum powder safety, could appear before juries.

The ruling is a big win for plaintiffs attorneys, who for years have faced accusations from Johnson & Johnson about allowing "junk science" into the courtroom.

"For four or five years, Johnson & Johnson has said this is 'junk science,' that there is no reliable science to support these theories," said Leigh O'Dell, a principal at Beasley, Allen, Crow, Methvin, Portis & Miles, who is co-lead plaintiffs counsel in the MDL. Wolfson's ruling found the  experts had "used reliable methodology and their opinions are substantially supported by the science."

"That completely obliterates that argument, and it's very significant for the overall litigation," O'Dell said.

Johnson & Johnson was reviewing the "procedural decision," which addressed the admissibility and reliability of scientific experts based on the U.S. Supreme Court's 1993 holding in Daubert v. Merrell Dow Pharmaceuticals, according to spokeswoman Kim Montagnino.

"We know that anyone suffering from cancer is searching for answers, which is why the science and facts on this topic are so important," she wrote in an email. "The Daubert decision is not a determination by the court on the validity of the plaintiff's allegations. Plaintiffs must meet their burden of proof, including both general and specific causation, at any trial that may be scheduled."

Johnson & Johnson has lost several verdicts in the talcum powder cases, including one last year awarding $4.7 billion to 22 women. On the science, Johnson & Johnson won a key 2016 ruling from Atlantic County, New Jersey, Superior Court Judge Nelson Johnson, who tossed the plaintiffs' experts over their "made-for-litigation" methods and tactics. In 2017, Los Angeles Superior Court Judge Maren Nelson tossed a $417 million talc verdict, affirmed on appeal last year, after citing an "ongoing debate in the scientific and medical community" over whether talc caused ovarian cancer.

The Daubert ruling comes nine months after Wolfson held a weeklong hearing at which eight of the 39 expert witnesses introduced in the multidistrict litigation testified about their research and qualifications. She reviewed the admissibility of those experts, five for the plaintiffs and three for Johnson & Johnson, as "representatives of each field of science involved in this case."

In October, plaintiffs attorneys sought to introduce additional evidence after Johnson & Johnson voluntarily recalled 33,000 bottles of its baby powder following the U.S. Food and Drug Administration's test results that found some had asbestos in them. In a footnote to Monday's order, Wolfson acknowledged "a number of studies that have been recently released on this topic," but did not consider them as part of the Daubert ruling. "However, this does not foreclose the possibility that the parties may seek leave from the court to supplement an expert's report based on any new and relevant studies," she added, and might "amend my rulings at a later time."

Her ruling, which also allowed three defense experts to testify, leaves a potential "battle of the experts" for future talcum powder trials.

"In conclusion, what remains clear from the general causation evidence relied on by the experts on both sides of this matter, is that there is scientific evidence supporting each side's opinion," she wrote. "At best, that the body of relevant scientific evidence is inconclusive and may be open to different interpretations—does not mean one side's interpretation is more reliable than the other."

Some of the plaintiffs' experts have appeared in state court trials, but most have not. The plaintiffs' experts include William Longo, founder of Materials Analytical Services, and Anne McTiernan, of the Fred Hutchinson Cancer Research Center in Seattle, both of whom testified last year on Capitol Hill about talc safety.

As to Longo, Wolfson found he could testify that Johnson & Johnson's talc products contained asbestos, but not that they caused exposure to asbestos. She also found McTiernan was "qualified to act as an expert in epidemiology," as were two other general causation experts.

Wolfson also found that Ghassan Saed, an associate professor at Wayne State University and plaintiffs' expert on ovarian cancer, could testify that talcum powder caused inflammation in ovarian cells, but not that it caused ovarian cancer, which was "unsupported by the findings of his study." She allowed his testimony, despite also finding "careless mistakes and shoddy record keeping" that raised questions about his credibility.

"Indeed, serious questions have been raised by defendants which a jury will have to weigh," she wrote.

Although all talcum powder trials have been limited to state courts in California, Georgia, Missouri and New Jersey, O'Dell said the ruling could have ramifications beyond the MDL.

"It has a huge persuasive effect on state court judges who have considered the evidence," O'Dell said. "They can see the detailed analysis that Judge Wolfson undertook in reaching her decision, the breadth of the record, which was quite extensive. The clear importance of the opinion is this is reliable science. You will see in cases going forward that state court judges will find probably quite easily that there is sufficient evidence for these experts to testify."