Arkansas State Trooper Under Fire for Punching 18-Year-Old Woman During Traffic Stop

A traffic stop in Arkansas went off the rails when a state trooper threw an 18-year-old woman to the ground and punched her ... it's on video, and now her attorney wants answers.

Dashcam footage from the August 1 stop shows Trooper Moisses Arellano ordering Alisa Hackett to place her hands on the trunk and take two steps back ... he then asks her to put a hand behind her back, and suddenly he's body slamming her to the pavement and punching her.

She repeatedly asks, "Sir, what did I do?" ... but within seconds, Arellano forces her to the ground and mounts her as she screams, asks to call her mother, and protests her arrest.

Arellano tells her he does not care and repeatedly orders her to turn around. When she shouts that he cannot punch her, he fires back ... "I'll punch you again if you don't f***ing turn around."

According to THV11, Arellano pulled her over after clocking her going 71 MPH in a 60 MPH zone. He reported finding a cold bottle of liquor in the passenger seat and said she was under 21.

Arellano wrote in his use-of-force report ... he decided to arrest her after learning she had received a warning during a similar stop days earlier. He said she pulled her arms away and she refused to roll onto her stomach ... prompting him to deliver one closed-fist strike to gain compliance.

Civil rights attorney Ben Crump is now calling on the Arkansas State Police to open a formal use-of-force investigation, publicly release its findings and turn over any previous reports involving Arellano.

Crump says ... "Arkansas State Police have to explain to the public how that is a reasonable response to a teenager at a traffic stop."