PORTLAND – A Portland man was sentenced to five years in prison for his 11th drunken driving conviction.

William Forbes, 50, who has been convicted of drunken driving 11 times since 1979, pleaded with a judge Thursday to send him into treatment rather than prison. Going to prison, Forbes said, could cause him to lose his place in line for a liver transplant he may need to survive.

But Assistant District Attorney Bud Ellis argued that compassion for Forbes must be balanced with Forbes’ pattern of drinking and driving that has made him a menace on the roads and landed him in and out of jails over the last 29 years.

“He has lost his right to be at liberty,” Ellis said. “He is a manslaughter waiting to happen.”

Justice G. Arthur Brennan agreed and sentenced Forbes to 10 years with all but five years suspended. With time off for good behavior and credit for the nine months he already served, Forbes will probably spend three to four years in prison.

Police stopped Forbes last September after another motorist told them he was driving erratically. The arresting officer said Forbes could barely stand up when he was stopped and refused to take a breath alcohol test.

Forbes carried a fake driver’s license, with his picture next to the name of his brother, who had died in 1997.

Forbes’ lawyer, Andrew Bloom, said Forbes is suffering from end-stage liver disease and that a doctor who examined him last year said he had no more than five years to live.

Bloom said Forbes had been living up to the conditions of his probation and attended his alcoholism treatment program for nearly three years, until his health took a turn for the worse last summer.

He said Forbes was depressed, possibly as a side effect of his liver medication, got drunk and went driving.

Forbes told the court he will never drink again.

“I tell you now, if I start drinking again, I will die. Not in a year, but right away,” he said. “The question is where I’m going to be when I die.”