A retired University of Tennessee engineering professor went on trial Monday, accused of passing secrets from his work on a U.S. Air Force contract to two foreign graduate students, one from China and the other from Iran.

J. Reece Roth, a 71-year-old expert in plasma physics, faces 18 counts of conspiracy, fraud and violating the Arms Export Control Act. He could receive up to 160 years in prison and more than $1.5 million in fines if convicted.

The law bars exchange of sensitive, though in this case not "classified," information to foreign nationals without permission.

A Knoxville company and a former protege of Roth have pleaded guilty and await sentencing.

Roth maintains he is innocent.

His lawyer, Thomas Dundon, told a federal jury in opening statements that it would be up to them to decide if the professor broke the law, saying the case against his client is not "black and white."

Roth "decided to operate under his own rules," Assistant U.S. Attorney William Mackie told the jury.

It was "not that he should have known (the rules), he did know," Mackie said. Yet Roth showed "a clear and willful disregard" for them.

Roth came under investigation in 2006 after University of Tennessee export-control officials discovered his use of foreign nationals in his UT lab on the Air Force work. Government agents searched his office and seized his laptop computer when he returned from a trip to China that year.

Roth, who according to his lawyer received no money from the Air Force contracts, surrendered voluntarily after his indictment in May.

The charges involve work performed from 2004 to 2006 on two Air Force contracts by Roth, UT graduates students Xin Dai of China and Sirous Nourgostar of Iran and the university spinoff company, Atmospheric Glow Technologies Inc.

The Air Force wanted to develop a lightweight flight control system for unmanned aircraft, or "drones."

Atmospheric Glow Technologies, with Roth as a consultant and subcontractor, promised a control system that would use electrically charged plasma, rather than mechanical flaps, to change airflow over the wings to lift the aircraft.

It was "a unique technology that has not been applied successfully to an airplane," Mackie said.

The first phase was fundamental research. The second was building a flying model and specialized testing equipment. The third was a full-size drone.

The project did not get beyond the second phase, and effectively ended when the U.S. flight agency refused to allow a plasma-controlled drone in the air over the United States, Dundon said.

Roth claims Xin Dai's involvement was mostly in phase one and did not involve protected information. The government counters that weekly test reports on the project's progress were passed to Xin Dai with Roth's knowledge and account for most of the charges against the professor.

Roth also is charged with taking some of these reports in a laptop computer to China in 2006 on a lecture trip, though Roth contends he was unaware of the contents, which were loaded into the machine by one of his American graduate students.

Xin Dai received his doctorate in electrical engineering in 2006. Nourgostar is still listed by UT as a student. Neither was charged.

Atmospheric Glow Technologies pleaded guilty in August to 10 counts of exporting defense-related materials, but as a bankrupt enterprise will ask for the court in sentencing for relief on any cash penalties. Roth protege Daniel Sherman also pleaded guilty on related charges and is awaiting sentencing. He claims he was unaware a law was broken.

U.S. District Judge Tom Varlan told the jury Monday the Roth trial could run into next week.