A man who was fired by IBM for visiting an adult chat room at work is suing the company for $5 million (£2.6 million), claiming that he is an internet addict who deserved treatment and sympathy rather than dismissal.

James Pacenza, 58, of Montgomery, says he visits chat rooms to treat traumatic stress incurred in 1969 when he saw his best friend killed during an Army patrol in Vietnam.

Mr Pacenza has filed papers in court stating that the stress caused him to become “a sex addict, and with the development of the internet, an internet addict.” He claimed protection under the Americans with Disabilities Act.

His lawyer, Michael Diederich, says that Mr Pacenza never visited pornographic sites at work, violated no written IBM rule and did not surf the web any more than other employees. He also says age discrimination contributed to IBM’s actions. Mr Pacenza, 55 at the time, had been with the company for 19 years and says he could have retired in a year.

IBM has asked Judge Stephen Robinson for a summary judgment, arguing that its policy against surfing sexual websites is clear. It also claims that Mr Pacenza was told that he could lose his job after an incident four months earlier, which Mr Pacenza denies.

Papers lodged with the court by IBM said that Mr Pacenza “was discharged by IBM because he visited an internet chat room for a sexual experience during work after he had been previously warned.”

The company also said that sexual behaviour disorders are specifically excluded from disabilities legislation and denied any age discrimination.

If it goes to trial, the case could affect how employers regulate web use that is not work-related, or how internet overuse is categorised medically. Stanford University issued a nationwide study last year that found that up to 14 per cent of computer users reported neglecting work, school, families, food and sleep to use the internet.

The study’s director, Dr Elias Aboujaoude, said then that he was most concerned about the numbers of people who hid their nonessential internet use or used the net to escape a negative mood, much in the same way that alcoholics might use alcohol.

Until he was fired, Mr Pacenza was making $65,000 (£33,000) a year operating a machine at a plant that makes computer chips. Several times during the day, machine operators are idle for five to ten minutes as the tool measures the thickness of silicon wafers.

It was during such down time on May 28, 2003, that Mr Pacenza logged onto a chat room from a computer at his work station. Mr Pacenza’s lawyer said that his client had returned that day from visiting the Vietnam Veterans Memorial in Washington and logged onto a site called ChatAvenue and then to an adult chat room.

Mr Pacenza, who has a wife and two children, said using the internet at work was encouraged by IBM and served as “a form of self-medication” for post-traumatic stress disorder. He said he tried to stay away from chat rooms at work, but that day, “I felt I needed the interactive engagement of chat talk to divert my attention from my thoughts of Vietnam and death.”

“I was tempting myself to perhaps become involved in some titillating conversation,” he said in court papers.

Mr Pacenza said he was called away before he got involved in any online conversation, but he did not log off, and when another worker went to the desk, he saw some chat entries, including a vulgar reference to a sexual act. He reported his discovery to his boss, who fired Mr Pacenza the next day.

Mr Pacenza says he would have understood if IBM had disciplined him for taking an unauthorized break, but firing him was too extreme. He argues that other workers with worse offences were disciplined less severely – including a couple who had sex on a desk and were transferred.

His lawyer said that IBM workers who have drug or alcohol problems are placed in programs to help them, and that Mr Pacenza should have been offered the same. Instead, he says, Mr Pacenza was told that there were no programs for sex addiction or other psychological illnesses.

IBM declined to comment on the case.