The US Justice Department is opening an investigation into the Louisville Police Department, which has been under scrutiny since the fatal shooting of a black woman, Breonna Taylor, in her home. “Promoting public trust between communities and law enforcement is essential to making both communities and policing safer,” Attorney General Merrick Garland said in announcing the investigation on Monday. It is the second significant “pattern or practice” investigation into police that the department has opened under Mr Garland, after the inquiries were largely abandoned during the Trump administration. Mr Garland said last week that the department had opened an investigation into policing practices in Minneapolis after George Floyd’s killing. An organisation representing police chiefs cautioned that such investigations should be “a collaborative effort”, and said the consent decrees that sometimes followed could prove costly and burdensome. “Our communities don’t want less cops, they want better cops, and investments must be made in terms of training, recruitment and data collection,” said Laura Cooper, executive director of the Major Cities Chiefs Association. “Above all, involvement and buy-in from everyone in the department is a must because without it, change and modernisation won’t take root.” Taylor, 26, was fatally shot in her apartment on March 13, 2020, when white plainclothes police officers forcibly entered it while investigating drug-dealing operations. Her killing became part of a larger movement protesting against racial bias in police departments, which led to nationwide demonstrations in the summer of 2020 and a greater focus on systemic racism in the US. A grand jury decided not to file murder charges against the officers involved in the shooting, although Louisville police eventually agreed to pay Taylor’s family $12 million and vowed to change their practices after the botched raid. Mr Garland said the Louisville Police Department took some steps towards needed reforms and that city officials pledged their support and co-operation as the Justice Department investigates. He said the inquiry “will be taken with one goal in mind: to ensure policing policies and practices are constitutional and lawful". "That is the same goal of our investigation into Minneapolis and of every pattern or practice investigation that the department undertakes," he said. The inquiry into Floyd’s killing came after a white former Minneapolis police officer, Derek Chauvin, was found guilty of killing Floyd, an unarmed black man, when he knelt on his neck for more than nine minutes in May 2020. The video of that killing ignited a summer of rage and the greatest racial reckoning in the US since the 1960s.