Mueller, former wife of actor Charlie Sheen, was arrested earlier in the year for drug possession and managed to avoid jail time. She later attended a rehab centre for her addiction.
The 34-year-old's spokesperson reported earlier this week that Mueller had returned to rehab after allegedly "partying for four days straight".
However, her lawyer has now told TMZ that Mueller only returned for a pre-scheduled maintenance programme approved by a judge.
Attorney Yale Galanter explained that the arrangements of Mueller's drug settlement stipulated that she return to rehab four times over the year.
Mueller apparently takes several drug tests a week as part of the terms of her probation, and remains clean.
Her parents have also confirmed that their daughter is still sober, insisting that she is simply "getting what she needs" from rehab.