LOS ANGELES -- The largest oil spill in U.S. history has unleashed a gusher of at least 250 class-action lawsuits that could eventually encompass millions of victims in a massive legal battle expected to stretch on for decades.

The first step in what many experts predict will be among the most complex environmental cases to hit the U.S. courts begins today, when an army of attorneys converges on Boise, Idaho. A federal panel there will begin to decide which judge or judges will oversee the cases, and where they will be initially heard.

"The stakes here are tremendous," said Loyola Law School civil procedure professor Georgene Vairo, an expert in complex litigation. "For a single-event type of incident, this is the biggest we've ever seen -- just in the range of claims, the government and private-party actions, the cost of claims, the insurance aspects. It's just the whole nine yards; it's huge."

Since the April 20 explosion of the Deepwater Horizon, hundreds of trial attorneys have descended on Gulf of Mexico states -- some garnering clients by advertising on billboards and holding town hall meetings. They have filed scores of lawsuits seeking damages expected to reach into the double-digit billions from BP, Transocean and other defendant companies.

The vast majority of the damage suits have been filed by fishermen, charter operators, restaurants and property owners claiming financial losses after the disaster shut down fisheries and pummeled coastal tourism. One suit seeks payouts for diminished property values of every land, home and business owner within five blocks of the Gulf shore.

Families of the 11 men killed in the disaster have filed wrongful-death suits. Seafood processors and marinas have sued over their dwindling revenues.

Complaints have flooded in from afar as well. An Ohio-based investment fund hit by falling oil industry share values is seeking damages. And South Carolina beach hoteliers has filed suit, claiming that they suffered from a spate of cancellations because tourists feared that the oil would reach around to the East Coast.

Environmental defense groups have sued on behalf of dead and injured wildlife. Veteran litigators have gone as far as to target BP with civil RICO actions -- accusing them of negligence so willful that they should be subjected to the steep penalties of the Racketeer Influenced and Corrupt Organizations Act.

"This spill has caused tremendous fallout in the legal arena," said New Orleans environmental attorney Allan Kanner, noting that the spill's scope far eclipses that of Alaska's 1989 Exxon Valdez spill, which caused more than 20 years of court wrangling.

Washington correspondent Daniel Malloy writes the "Pittsburgh On The Potomac" blog exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.