McCready was 10 minutes late for the start of court, prompting Judge Seth Norman to tell the singer she was in contempt of court and he would decide later what punishment she will face. The sentence could range from a verbal rebuke to 10 days in jail.
McCready, 30, has encountered a string of legal and personal problems since her 2004 conviction for fraudulently obtaining prescription painkillers.
In May 2005, she spent a night in jail after the DUI arrest that has resulted in her being put on trial. Two days later, she was treated at a hospital for injuries suffered in a domestic beating.
Since then she has sued her former boyfriend, William McKnight, over the beating and was charged with violating her probation on the drug charge by failing to check in with her probation officer and leaving the state without permission to go to Florida. Her trial on that charge has been delayed to await the outcome of the DUI case.
McCready also has acknowledged she tried twice to commit suicide and had a child earlier this year by McKnight.
The DUI case will center on a video of the field sobriety test McCready took after she was stopped for speeding. McCready refused to take a breath test, but the arresting officer said she smelled of alcohol and acknowledged she had been at a bar earlier.
A jury was seated Monday and opening statements were set for the afternoon.
McCready had a No. 1 hit in 1996 with "Guys Do It All the Time."