...gray market to boost their profit margin, brand awareness and residual value. Such activity would waive Cat's right to relief, lawyers say.

Indeed, defendants claim that Cat is the biggest importer of gray excavators through a subsidiary called Caterpillar Redistribution Services Inc., one of the engines behind www.catused.com, an online trading post.

"They sell the same gray market machines of which they are complaining," says Vander Schaaf.

Hoss echoes, "How is it not gray for them, but it's gray for me?"

The outcome of the case could have broad implications for suppliers and contractors. Used Cat excavators, which command a premium price of 5% to 20% in the domestic market, represent as much as 10% of auctioneers and dealers' gross sales each year, defendants say.

If Cat wins, users would lose access to these popular machines unless they went to an authorized dealer. They also would not be able to import back into the U.S. excavators used on projects elsewhere in the world.

For several defendants, the cost of fighting Cat in court far outweighs their sales of gray imports. "It's a matter of principle," says Greenberg. "We're not going to let the 700-pound gorilla step on us."

Others have decided to exit. Rather than fighting in court and racking up hundreds of thousands of dollars in legal fees, several companies, including Ritchie Bros. Auctioneers Inc., Richmond, British Columbia, settled with Cat earlier this year. Terms of their agreements have not been disclosed.

"I think they traded Park Place for Boardwalk," says Lyon. Ritchie Bros. is the world's largest equipment auctioneer, earning $57.2 million last year on gross sales of $2.7 billion. It declines to comment on the ITC suit.

The domestic excavator market has doubled over the past four years due to hot demand for work around sewers, pipelines, highways, mines and buildings, and it remains highly competitive.

Last year, Cat lost market share to Kobelco, Komatsu, Link-Belt and Volvo, according to Mundelein, Ill.-based machinery analyst and consultant Manfredi and Associates Inc. But Cat still held a higher share than anyone else, with 32.5% of the market.

Locking up the used market could be a strategy for Cat to hold on, experts say. "Caterpillar has endeavored to participate actively in the after-sales revenue stream--for the past 15 or 20 years," says Frank Manfredi, president of the eponymous consulting firm. "I suppose that this is a negative for users in the long run, because overall pricing will go up."

Yet Manfredi adds that manufacturers are right to focus on things like safety. "The manufacturers have a legitimate concern," he says. "Whether or not Caterpillar is being overzealous about this, I can't tell."

If Cat wins, lawyers say it could open the floodgates to more restrictions on other types of machines, such as wheel loaders and backhoes. If the dealers win, manufactures may be less aggressive to fight gray imports.

"This case will stand as precedent," says Vander Schaaf.