ATLANTA (AP) — A Georgia sheriff standing trial on federal charges that he abusing detainees’ rights by strapping them into restraint chairs as a form of punishment denied wrongdoing Thursday, insisting the chairs are safe as long as jailers follow provided rules.

Clayton County Sheriff Victor Hill took the witness stand a day after prosecutors rested their case in U.S. District Court in Atlanta. They say Hill violated the rights of seven detainees at the Clayton County Jail whose placement in restraint chairs was unnecessary, was improperly used as punishment, and caused pain and bodily injury.

Hill testified that the chairs are used to protect jail staff and detainees, The Atlanta Journal-Constitution reported. He said some are strapped into the devices as a precaution because they exhibit “pre-attack indicators,” or behavior that suggests they might become violent.

“The best proactive use of force is restraint,” Hill said.

Hill is widely known as one of metro Atlanta’s most flamboyant lawmen. He calls himself “The Crime Fighter” and uses Batman imagery to promote himself on social media and in campaign ads.

Hill has pleaded not guilty to the civil rights charges.

The sheriff testified he was convinced the restraint chairs were safe when he first purchased them for the jail in 2018. He also said jail staff have been provided with clear rules for using the chairs, including requirements that jailers check detainees every 15 minutes they spend strapped into the chairs.

Hill also denied responsibility for two former detainees who testified in the case Tuesday. They said they had spent hours in the chairs with their hands cuffed behind their backs and arms bound. Both men said they were restrained for so long that they urinated on themselves.

This is Hill’s second trial on criminal charges. Clayton County voters reelected Hill in 2012 while he was under indictment the first time, accused of using his office for personal gain. He beat those charges.