Kiyoski Matsumoto, an engineering executive with Toyota Motor Co., Ltd., attended hearings at the Environmental Protection Agency in Washington, D.C., in mid-April 1972.

While there, he sketched the General Motors Corp. catalytic converter on display. That's something both GM and Toyota agree on.

Whether Toyota then copied GM's converter and whether GM's patent on that device is valid, are points of contention at a federal trial here. Three days of testimony were head two weeks ago.

There's no argument that the air polution control devices on Toyota, Datsun, American Motors Corp., and GM cars share much in common and differ greatly from the converters on Ford Motor Co. and Chrysler Corp. cars.

AMC buys its converters from GM. Nissan Motor Co., Ltd., which makes Datsuns, has paid GM more than $1 million in license fees for the device.

The issue is a particularly important one because it was GM that broke the solid auto-industry front - domestic and foreign - against the converter back in 1972. That move in turn led directly to the EPA setting emmission limits that required the device, and to the need to distribute the lead-free gasoline that it requires.

GM is arguing before U.S. District Judge Carl B. Rubin that Toyota copied its device and before stealing the GM design never had a converter that lasted more than 12,000 miles.

GM first filed for a patent in September 1971 and was granted it in December 1974.

Hugh Chapin, a New York patent attorney representing Toyoto, said he would not argue the novelty of the GM patent but would argue that the basics for it existed as prior art. The subject matter for GM's patent "would have been obvious to a man of ordinary skill in this area. Therefore the patent is invalid," Chapin said.

He told Judge Rubin extensive work on catalytic converters was performed between 1960 and 1966, particularly to control Los Angeles smog.

The topic then essentially died for three years until it was revived by the Prospects of the 1970 Clean Air Act, Chapin said.

George Frost, GM's top patent expert, said he expects that Toyota's lawyers will argue that the prior art involves to some degree "things our own people did internally. We do not think that any unpublized, internal works can be claimed as prior art," Frost said.

GM has made no mention of what kind of money it would demand if it wins the lawsuit.

Both Toyota and GM had established project engineering teams on the catalytic converter by the first month of 1970. "At that time, various kinds of converters were well known to people in both GM and Toyota," Chapin said.

The GM patent doesn't involve exotic chemistry but simply the way that certain metal plates are bent and attached together, he argued.

"It seems clear that General Motors just chose people who had experience at forming and joining metals" Chapin said.

The converters used by GM, AMC, Toyota and Datsun all have small metal-like beads held in a strong metal container. The beads are coated with an ultra-thin layer of platinum.

When exhaust gases are passed over the beads, the platinum speeds the chemical conversion of air pollutants to water vapor and other harmless gases.

Instead of beads, the converters used by Ford, Chrysler and others have a honeycomb made from baked clay that is also coated with platinum.