BANGOR – The former assistant women’s basketball coach at the University of Maine who pleaded guilty last week to drunken driving will not go to jail even though state law required her to spend 48 hours behind bars because her blood alcohol level was nearly twice the legal limit.

Katherine Karlsson, 37, of Stillwater instead was ordered to pay by June 28 an $800 fine, $300 more than the mandatory minimum. Her driver’s license also was suspended for 90 days.

Karlsson’s Bangor attorney, Lawrence Lunn, said in a statement issued Monday that “she is pleased with this result and very relieved to have the entire matter behind her.”

Lunn entered a not guilty plea to operating under the influence of intoxicants on the ex-coach’s behalf in November. The attorney also entered a change of plea for Karlsson and argued that she not be sentenced to jail time on Thursday in 3rd District Court in Bangor.

Karlsson never appeared before a judge. That is not unusual in similar cases where defendants hire their own attorneys.

The former coach was arrested shortly before midnight on Nov. 5 on Mount Hope Avenue in Bangor by Maine State Trooper Christopher Hashey. Her blood alcohol level was 0.15 percent, nearly twice the legal limit of 0.08 percent, according to the police report.

In a decision made public Monday, District Court Judge Robert E. “Buddy” Murray found that prosecutors could not prove beyond a reasonable doubt that Karlsson’s blood alcohol level actually was .15 percent. Due to the margin of error in the alcohol breath testing process, Karlsson’s blood alcohol level could have been anywhere from 0.1175 to 0.1825 percent.

Despite the public perception that such tests are accurate, their margin of error rate is more than 15 percent, according to Robert Morgner, a chemist for the Department of Health & Human Services. That rate is due to the differences in the way people of varying weights and ages absorb alcohol and the machine’s margin of error. Blood alcohol tests are considered to be exact.

State law requires that anyone convicted of driving under the influence of intoxicants with a blood alcohol level of .15 or more spend 48 hours in jail, pay a $500 fine, and have his or her license suspended for 90 days. Drivers with a blood alcohol level between .08 and .14 percent are required to pay the fine and have their licenses suspended.

Even if she had been sentenced to 48 hours in jail, it’s unlikely Karlsson would have served her time in a cell in the Penobscot County Jail. James Aucoin, assistant district attorney for Penobscot County, said last week that she would have been eligible for the alternative sentencing program.

That program allows first-time offenders to serve their jail time over a weekend without actually spending the night in a cell. Instead, they might stay at a local school or other public building and paint or do minor repairs but would not be allowed to leave the facility voluntarily.

Karlsson’s former boss, ex-Maine head coach Ann McInerney, was the only passenger in Karlsson’s 2005 blue Volkswagen Jetta when she was stopped, according to the trooper’s report. McInerney refused to cooperate with the trooper and left the scene while he was questioning Karlsson.

McInerney resigned in April but did not give reasons for her resignation, according to a story published in the Bangor Daily News.

After her arrest, Karlsson was suspended from her job for three games and McInerney was reprimanded in a Nov. 30 letter from President Robert Kennedy. McInerney issued an apology Dec. 1.