In the first day of defense in the murder trial of Derek Chauvin, his attorneys argued Tuesday that the former Minneapolis police officer was justified in his use of force against George Floyd.They also called witnesses to the stand who told the jury about Floyd's past drug abuse.Chauvin, who is white, has pleaded not guilty to murder and manslaughter charges in the case of Floyd, a 46-year-old Black man whose death last summer sparked protests against racism and police brutality around the world.Chauvin's lead attorney Eric Nelson called on Barry Brodd, a use-of-force expert, to testify on Tuesday.BRODD: "I felt that Officer Chauvin's interactions with Mr. Floyd were following his training, following current practices in policing, and were objectively reasonable."His testimony contradicted several prosecution witnesses, including the city police chief, who said earlier in the trial Chauvin had no justification for kneeling on Floyd's neck for more than nine minutes.Seeking to challenge the claim that Chauvin's use of force was justified, Prosecutor Steve Schleicher got Brodd to agree that Chauvin continued restraining Floyd even after he had stopped resisting.SCHLEICHER: "From this point and to the point at which the EMTs arrive, tap on the defendant's shoulder and take Mr. Floyd, place him onto the gurney, from this point to that point, Mr. Floyd wasn't resisting, was he?"BRODD: "No."Chauvin's defense team also sought to highlight Floyd's apparent drug abuse history to argue that he died of an overdose, rather than lack of oxygen caused by Chauvin's actions, as the prosecution contends.One of their witnesses was retired paramedic, Michelle Moseng, who treated Floyd after he was arrested in 2019. Moseng said that Floyd told her he consumed opioids and that he was addicted.Tensions surrounding the trial are running high this week after another Black man, Daunte Wright, was fatally shot by a police officer during a traffic stop, just 10 miles away from where Floyd was killed, in a suburb of Minneapolis.