The Baby hitmaker was taken into custody after he was reportedly caught drag racing and he was subsequently charged with driving under the influence (DUI), resisting arrest without violence and driving with an expired driver's licence.Last month, 10 hours of surveillance footage featuring Bieber's time behind bars was released to the media, and in one clip the 20 year old appeared to be struggling to walk in a straight line.And now a Miami Beach police document, released on Tuesday, details his performance on various sobriety tests.It also documents Bieber's claims that he was nursing an injured foot following a skateboarding accident three months earlier, which left him unable to walk properly.The report reads: "He (Bieber) appeared to have great difficulty." The arresting officer also noted that the singer appeared to "sway and have leg tremors during one of the tests, and also winced as if in pain."The documents also detail Bieber's defensive attitude towards the cops while in custody, suggesting he was initially "agitated and condescending" and frequently used profanity.The report quotes Bieber as saying: "I'm 19 years old. I'm just out having a good time. What were you doing when you were 19?"The officer told the singer that he was not driving around in a Lamborghini at his age, to which Bieber responded: "Yeah, well, I bet you didn't have millions of dollars in your bank account either."The singer also mentioned that he took anti-anxiety medication whenever he feels "closed in".Results from drug tests taken by police suggested the presence of the active ingredient in marijuana and Xanax, an anti-anxiety drug, in Bieber's system at the time of his arrest. A Breathalyzer test detected traces of alcohol in his system, but it was below the 0.02 blood alcohol level allowed for drivers under the age of 21.Bieber will head back to Miami to face trial on 5 May.