The New Jersey managing partner of Patton Boggs has resigned seven years after establishing the office, amid layoffs, flagging revenues and a revamping of partner compensation.

John McGahren, an environmental litigator, departed in the middle of a vast downsizing of the Newark office from 80 lawyers in the spring to 48 now.

A staffer answering the telephone said McGahren no longer worked there and forwarding information was not available, and McGahren did not respond to a message left at his home.

But a source familiar with the office's operations says that McGahren left voluntarily and that an announcement about his new job will be made after Labor Day.

His departure comes as the 400-lawyer firm, based in Washington, D.C., is in the midst of an upheaval. It laid off 65 lawyers and staff in March and, according to an Aug. 8 article in The Wall Street Journal, more than 20 partners defected during the summer.

The Newark office was especially hard-hit by the wrap-up of litigation over health problems by workers who responded to the attacks on Sept. 11, 2001, according to a second source familiar with the firm.

The litigation had been a mainstay of the office, but was resolved in 2011 with a $625 million settlement.

The office had represented New York City and some of its contractors in the World Trade Center litigation. Other clients include Ford Motor Co., Continental Airlines and Monsanto.

McGahren and a colleague, James Tyrrell Jr., were working for Latham & Watkins in Newark in 2006 when they led a 25-lawyer exodus to the new Patton Boggs offices in Newark and New York.

Tyrell became head of the New York office, which focused on finance, capital markets, trade regulation and risk management.

McGahren was made managing partner of the Newark office, which focuses on complex commercial and environmental litigation. His practice includes Superfund-related hazardous waste litigation and counseling industrial clients on federal regulatory matters and state laws.

Latham & Watkins' Newark office, once 40 lawyers strong, never recovered from the exodus. In June 2012, it reassigned remaining lawyers and staff from Newark to New York, and downsized to a small office for the convenience of clients.

Tyrell, who remains at Patton Boggs, did not return calls.

Revenues and other financial indicators plummeted at the firm between 2011 and 2012, according to The American Lawyer magazine.

Gross revenue dropped from $339.5 million to $317.5 million, net operating income from $90 million to $77.5 million, revenue per lawyer from $690,000 to $655,000, profits per equity partner from $865,000 to $735,000, and average compensation for all partners from $625,000 to $575,000.

In a March 1 article in The Wall Street Journal, firm managing partner Edward Newberry said the firm had notified 18 partners that their contracts would not be renewed if their performance did not improve.

Patton Boggs' communications manager, Natalie Gewargis, said she would gather information about McGahren and the Newark office but did not reply by deadline.

Patton Boggs has offices in Anchorage, Dallas and Denver as well as Newark, New York and Washington, D.C.. It also has four locations in the Middle East.