The Real Housewives of Atlanta alum came to the 20-year-old's defense in an Instagram Story on Tuesday.
"Ariana was involved in a minor fender bender. When police arrived on the scene, the investigating officer immediately initiated an investigation for DUI of alcohol," wrote Zolciak-Biermann, 44. "Despite Ariana's constant invocation that she was upset and anxious from the minor accident, the officer incorrectly concluded she was impaired. That was not the case."
Zolciak-Biermann declared that Ariana was "not impaired by any substance, including alcohol or marijuana."
"Since she was being cooperative and honest, she admitted to consuming marijuana the day before, meaning over 24 hours prior to her contact with the law," she continued. "In addition, the arresting officer, as evidenced by his own police report, charged Ariana with impairment by alcohol. She wholly denies these allegations and intends to fight these charges because she is not guilty of them."
She concluded, "We appreciate the general public allowing this case to be tried on its merits, and not rhetoric or incorrect conclusions."
This past weekend, Ariana was arrested after being involved in a collision with another vehicle while driving a black Mercedes G-Wagon. Upon being taken to Forsyth County Jail, she was charged with three misdemeanors: driving under the influence of alcohol, improper/erratic lane change and underage possession/purchase of alcohol.
Ariana was later released on a $5,120 bond.
According to a police report obtained by PEOPLE, an officer claimed to have smelled alcohol on Ariana's breath. She has denied she was drinking but did admit to smoking a THC vape pen the night before — an item that an office retrieved from her bag.
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Attorney Justin Spizman, of Hawkins Spizman law firm, previously told PEOPLE Ariana "denies these allegations and intends to fight these charges because she is not guilty of them."
Ariana's on-and-off boyfriend Hudson McLeroy was also arrested at the time for allegedly driving under the influence, furnishing alcohol to a minor and violating the conditions of his limited driving permit.
Zolciak-Biermann is also mother to 25-year-old daughter Brielle Biermann. The former reality star additionally shares Kroy Jagger, 10½, Kash Kade, 9½, and 8½-year-old twins Kaia Rose and Kane Ren with husband Kroy Biermann. The couple has been married since 2011.