Patton Bloggs is a law firm in DC that has a pedigree and profile almost as distinctive as the Lincoln Memorial. But will the firm itself become a monument to what was . . and what could have been?

Or will the firm’s entanglement with the oil monolith Chevron ensure that the firm simply disappears in the proposed merger with Squire Sanders.

Bloomberg BusinessWeek writer Paul Barrett wrote this week that Patton Boggs was severely shaken by the global recession, together with issues facing the law industry and bad management by lawyers who thought they were great chief executives

The most notorious examples were New York’s Dewey & LeBoeuf and Washington’s Howrey, both of blessed (or cursed, depending on one’s perspective) memory.

Patton Boggs, for decades a regulatory and lobbying powerhouse with ties to the Boggs political dynasty, has been showing signs of an elite legal brand likewise about to crumble and go away.

When I last checked, Patton Boggs was acknowledging the collapse of merger talks with Locke Lord, a firm prominent in Texas but with nothing like the national panache that goes with the Boggs banner. That failed union had the whiff of desperation as far as Patton Boggs was concerned

Last week came word that Patton Boggs was consolidating and shedding lawyers (again), shutting an office in Newark, and talking about another merger—this time with Squire Sanders, a large national firm started in Cleveland. (See: Lawfuel.com here)

Beyond the hazards facing many of its peers in the 400- to 750-lawyer range—firms that lack the worldwide reach of multithousand-attorney behemoths and at the same time don’t enjoy the nimbleness of a boutique—Patton Boggs has fallen victim to a more unusual malady: overreliance on marquee litigation that dries up or goes awry. It saw one gusher of a case—the courtroom battle over Sept. 11 liability—reach a natural resolution in 2011. The legal fees from representing New York City in its litigation against injured World Trade Center firefighters and rescue workers was lucrative while it lasted. But to the chagrin of attorneys, every disaster eventually comes to an end. Patton Boggs apparently grew too dependent on the Sept. 11 case.

The same rainmaking partner who presided over the Sept. 11 litigation got Patton Boggs involved in a separate matter that has cost the firm millions of dollars in billable hours with no prospect of a payout soon. In 2010, James Tyrrell, a prominent mass injury defense lawyer, put Patton Boggs’s resources and reputation on the side of Ecuadorian villagers suing Chevron over oil pollution in the Amazon. The villagers won an historic $19 billion verdict in 2011. Rather than comply with the judgment of an Ecuadorian trial court, however, the oil company turned on the plaintiffs’ lawyers, including Tyrrell and Patton Boggs.

A furious side battle erupted pitting Tyrrell against Chevron’s main outside firm, Gibson, Dunn & Crutcher, with allegations of fraud and intimidation flying in all directions. Tyrrell found himself allied with a controversial New York activist-lawyer named Steven Donziger, whom Chevron is suing in a civil racketeering suit in federal court in New York. Accused of fabricating evidence and other misconduct in Ecuador, Donziger denies wrongdoing.