Justin Timberlake Failed Field Sobriety Tests Before DWI Arrest: Police

Justin Timberlake's lawyer may be convinced the singer wasn't intoxicated during his DWI arrest ... but new police documents paint a totally different picture of JT's state on June 18.

In the documents ... the pop star verbally refused a Breathalyzer test 3 times after he was pulled over by rookie cop Michael Arkinson for blowing through a stop sign in Sag Harbor.

Per Arkinson's notes, he followed field procedure, as he observed several signs of JT's alleged intoxication ... including the odor of alcohol, glassy eyes, divided attention, and an unsteady foot. Daily Mail was first to report the news.

It appears JT's balance was the final straw for Arkinson, who noted the singer struggled to perform a number of field sobriety tests. For starters, during a walk-and-turn test, Justin was allegedly "very unbalanced" and failed to correctly follow instructions.

The test itself required Justin to walk in a straight line while taking 9 steps ... with his heel to be placed directly in front of his toe. Justin was then asked to turn and repeat the steps. According to the report, Justin took an improper turn during this test ... as he "turned [the] wrong way" and "used [his] heel."

Justin was further instructed to raise one foot off the ground for 30 seconds without moving ... but he failed to keep his balance ... and he put his foot down before the allotted time was up, according to the report.

Between these results and his repeated refusal to take a Breathalyzer, Arkinson made the decision to arrest Justin, who was handcuffed and taken to the local police station.

Arkinson took an inventory of JT's belongings during the arrest, which included a Rolex watch, a black vape pen, a gold ring and some cash in his wallet.

This account is strikingly different from Justin's lawyer's assertion ... the attorney previously stated the singer was not intoxicated during the traffic stop, and asked for the court to dismiss the case over paperwork errors.