Weil Gotshal and Manges, the 1,000-lawyer New York firm, on Monday opened a three-lawyer office in Princeton led by Dechert veteran litigator Diane Sullivan.

The office, Weil, Gotshal’s 10th in the country and 21st worldwide, will handle trial and general litigation work, including complex commercial matters, class actions and product liability/mass torts.

It also brings the firm geographically closer to many of its pharmaceutical and life sciences clients.

The other attorneys in the new office are two of three litigators Sullivan led to Weil Gotshal on Feb. 13 — associates Adam Tolin and Allison Brown from Dechert in Philadelphia, who also worked closely with Sullivan. Partner Kathleen O’Connor, a former in-house attorney for Merck & Co. Inc., who later worked with Sullivan at Dechert in Princeton, is based in New York.

Sullivan, a defense veteran of trials over tobacco, Vioxx, Seroquel and Vytorin among others, says she was courted by Weil Gotshal for about two years.

She says that after focusing on pharmaceutical product liability and mass tort cases for many years, she wants to do more commercial litigation, and joining Weil Gotshal will help her toward that goal.

Weil Gotshal’s strength outside the United States and in practices such as securities and employment law will position her to expand her practice, says Sullivan.

“The more people I met at Weil, the more I appreciated that the opportunities were significant, both for our clients and for me,” Sullivan says.

Sullivan, who will be partner in charge of the Princeton office, would not say whether the firm plans to add more lawyers beyond the current three.

She also declines to discuss what clients she brought with her or disclose how large the office is, except to say it had a few extra desks if the firm chose to hire more lawyers.

Sullivan and her team won a defense verdict last year for Philip Morris in a suit by the city of St. Louis and a group of hospitals seeking $455 million plus punitives for treating tobacco-related illnesses. The team also scored a win on behalf of AstraZeneca in a product liability suit over the company’s anti-psychotic drug Seroquel.

Sullivan won a no-cause verdict before Atlantic County Superior Court Judge Carol Higbee in the first Vioxx trial in New Jersey, in 2005.

But the judge granted the plaintiff a new trial after finding Merck withheld data from a study of adverse effects the drug had on users’ hearts. At retrial, the plaintiff was awarded $47.5 million in compensatory and punitive damages. The jury rendered a no-cause verdict for a plaintiff whose case was tried at the same time.

In 2006, Sullivan scored a defense verdict for Merck in the first case involving long-term use of Vioxx, also before Higbee. And in 2002, she obtained a defense verdict for Baxter Healthcare Corp. and Allegiance Healthcare in the first latex glove allergy claim tried to a jury, in Minnesota.

Last month, after Sullivan and her team defected, James Quinn, co-chairman of Weil Gotshal’s litigation department, said the firm already has some overlapping clients with Sullivan in the pharmaceutical industry, including Merck and Pfizer, but he insisted that attracting new work was not his firm’s main objective in wooing Sullivan.

Rather, he said, recruiting her is part of a broader push to bring more trial-ready talent to the firm.

“We have a number of people, myself included, who try cases a lot, but to have one of the top trial lawyers in the U.S., particularly a woman, it doesn’t get any better than that,” Quinn said.

Weil Gotshal issued a statement from executive partner Barry Wolf, who said, “We have executed a thoughtful and measured approach toward gaining additional scale in key regions. Opening a New Jersey office allows us to have a closer physical presence to many of our pharmaceutical and life sciences clients.”

Dechert spokeswoman Beth Huffman said in a statement, “Diane and Kathleen have been valued members of our firm for many years. We understand that they would like to change the focus of their practice and we wish them well.”