A former Army scientist's work and his public advocacy for bioterrorism defense led to the dismissal of his libel suit charging the New York Times with publishing columns unfairly linking him to the 2001 anthrax attacks.

In a 28-page opinion released yesterday, Judge Claude Hilton of Alexandria, Va., concluded that the scientist, Steven Hatfill, was a public official and a public figure. Those findings set a high bar for Mr. Hatfill's suit, requiring him to present evidence that the author of the columns, Nicholas Kristof, knew that the columns were false or had strong reason to think they were untrue. Judge Hilton said he dismissed the case last month before trial because there was no way Mr. Hatfill could make such a showing.

"Plaintiff was a vocal critic of the government's level of preparedness for a bioterrorist attack. His lectures, writings, participation on panel, and interviews, as well as his own resume, led many to consider Plaintiff an expert in the field of biological weaponry," Judge Hilton wrote. "Plaintiff should have foreseen that by providing interviews, delivering lectures, and publishing articles on the subject of the bioterrorism threat, a public interest in him would arise."

Judge Hilton's opinion offers no criticism of Mr. Kristof and suggests that he acted responsibly in preparing the columns. "The evidence in the record demonstrates that Mr. Kristof did not believe that any of his statements were false," the judge wrote, adding that the Times "made efforts to avoid implicating" Mr. Hatfill.

" Mr. Kristof reminded readers to assume Plaintiff's innocence, and highlighted the fact that Plaintiff was viewed by his family and friends as a patriot who could not have perpetrated the crime in question," Judge Hilton wrote.

An attorney for Mr. Hatfill, Thomas Connolly, vowed an appeal. "The opinion is more or less what we expected, given the judge's earlier statements," the lawyer said. "We expect to prevail on appeal like we've done before."

It was the second time that Judge Hilton has thrown out Mr. Hatfill's suit. In 2004, the judge dismissed the case after finding that the Times columns accurately described the federal investigation and did not accuse Mr. Hatfill of responsibility for the anthrax attacks. A federal appeals court overturned that decision, holding that a jury could find that the columns implied the scientist's guilt.

Mr. Connolly said there was evidence that Mr. Kristof knew that his reporting was unreliable. "There enough evidence on the record demonstrating the falsity of the statements to permit this to go to trial with a jury," the attorney said. Only one of the six columns in question mentioned Mr. Hatfill by name, and that was after the Justice Department identified him as a person of interest in the probe. The other five columns referred to him as "Mr. Z," though Mr. Hatfill contends his associates knew he was the one being discussed.

The columns, published in 2002, faulted the FBI for failing to investigate Mr. Z adequately in connection with mailing of anthrax to various news outlets. Five deaths were attributed to the tainted mailings. FBI investigators searched Mr. Hatfill's home and a storage locker, but neither he nor anyone else has been charged in the five-year-old case.