The apparent participation of off-duty officers in the rally that morphed into a siege on the U.S. Capitol building Jan. 6 has revived fears about white supremacists within police departments. These concerns are not new. White supremacy, the belief that white people are superior to other races, has long tainted elements within law enforcement. As I testified before Congress just months before this assault, there is a long history of racism in U.S. policing – and this legacy may have contributed to the violence in the Capitol in Washington, D.C. Reports of officers involved in an attack in which the symbols and language of white supremacy were clearly on display are concerning. But so too, I believe, is a policing culture that may have contributed to the downplaying of the risk of attack before it began and the apparent sympathetic response to attackers displayed by some police officers – they too hint at a wider problem. (…) But the percentage of police officers who hold views in support of white identity extremism may be at least as high or higher – white people are overrepresented on police forces cross the country. And surveys have found that police officers – especially white ones – diverge from the wider public on issues of race. A 2017 Pew poll found that 92% of white officers believe that the U.S. had made the reforms necessary for equal rights for Black Americans. This compared with just 29% of Black officers and 48% of the general public, including 57% of white Americans. This leads some to wonder whether police are more sympathetic to the rhetoric of Trump and others.