William Frentzen

William Frentzen, a partner at Morrison Foerster, is known for handling complex litigation, including white-collar defense and commercial litigation. He also has a notable background as the former chief of the corporate and securities fraud unit for the U.S. Attorney’s Office for the Northern District of California. During his tenure at the Department of Justice, Frentzen successfully tried over 40 federal jury trials.

In recent years, he has been involved in several high-profile cases. One notable matter is representing Inland Empire Waterkeeper in a Clean Water Act citizen suit against Corona Clay Co. This case was significant for being the first jury verdict in favor of a plaintiff in a Clean Water Act citizen suit following the U.S. Supreme Court’s decision in County of Maui v. Hawai’i Wildlife Fund.

Frentzen successfully argued the case, resulting in a jury verdict that held Corona Clay liable for thousands of violations.

He said he was faced with a short period of time to prepare for a trial that had resulted in his client losing the first trial.

“In the intervening period, the Supreme Court raised the burden on the plaintiff for the retrial regarding how to prove that an indirect discharge of pollutants is the functional equivalent of a direct discharge,” Frentzen said. “We prepared a new expert witness in a short period of time and prepared to cross-examine two defense experts. In the end, the jury agreed with us and we won on thousands of violations of the Clean Water Act.”

Another major case involved defending Lime (Neutron Holdings, Inc.) against Khosla Ventures in a dispute centered around allegations of fraud and interference with contractual relations. Frentzen successfully argued for summary judgment, which was granted in full by the court and upheld on appeal, representing a significant victory for Lime.

He said he was able to convince a San Francisco Superior Court judge that the plaintiff’s claims of fraud and tortious interference with business were too weak to proceed to trial through a motion for summary judgment.

“Our theory was that the plaintiff had no basis to show that it was our client who interfered or committed any fraud,” Frentzen said. “The trial court agreed, granted a rare summary judgment, and it was upheld on appeal.”