California policing played a significant role in the development of federal oversight of local law enforcement more than 20 years ago. Now, with the new Justice Department resistant to that power, California could show state and local governments how they can exert more control.

Rodney King’s infamous 1991 beating by Los Angeles police officers, and the subsequent L.A. riots, prompted Congress to expand the attorney general’s authority to monitor police departments. Former President Bill Clinton’s 1994 Violent Crime Control and Law Enforcement Act, a law frequently criticized today as fuel for mass incarceration, included a small statute that authorized the nation’s chief law-enforcement officer to investigate and file civil litigation against departments that demonstrate a “pattern or practice” of unconstitutional conduct.

The administration of former President Barack Obama embraced its oversight authority, particularly in its final years; it investigated 25 police departments, including those in Baltimore and Chicago. But President Trump’s Attorney General Jeff Sessions has no intention of following suit. He has sharply criticized federal investigations, arguing that they’re bad for police “morale,” and has said it’s “not the responsibility of the federal government to manage non-federal law-enforcement agencies.”

Critics perceive Sessions, and the president he serves, as more interested in protecting the police than public safety—a quality often attributed to the larger Republican Party. But even heavily Democratic areas have mixed track records when it comes to addressing police misconduct. That includes California, which is one of the country’s most liberal states but home to some of its deadliest police. Both California’s reforms and shortcomings are worth examining during the Trump era, as activists and researchers consider state-level measures to counter possible federal inaction.

One policy currently being debated among police-reform advocates is the adoption of a statute that would allow state attorneys general to investigate and mandate structural changes within troubled departments, just as the federal Justice Department can. These changes can vary, but could include amending a department’s use-of-force policy or requiring bias training. The proposal has its origins in California, as it is the only state in the country that explicitly authorizes its attorney general to intervene in this way.

William Lockyer was the first California attorney general to exercise that power, after four Riverside police officers shot and killed a 19-year-old black woman in 1998. The shooting ignited community protests and attracted attention from civil-rights activists Al Sharpton and Jesse Jackson. The Riverside County district attorney invited Lockyer to review the evidence and circumstances of the case.

Though the state did not have enough to bring criminal charges against the officers, Lockyer told me, he launched a civil-rights investigation into the Riverside Police Department’s policies and practices. In 2001, he filed a judgment forcing the department to implement specific reforms within a five-year period. The changes included using more experienced officers on overnight shifts and implementing community policing: assigning officers to monitor specific neighborhoods on a long-term basis and build trust with residents.

“The police chief and many others said after the fact that this was the best thing to ever happen to the Riverside Police Department; it really professionalized the force,” Lockyer said. “I think it makes sense to have some external review, whether federal or state, as a way to check local politics and pressures that can stand in the way of reform.”

The Riverside reform agreement presents one case study to examine stronger state intervention in local policing, but state oversight is not an easy fix. The California attorney general has had intervention authority for 16 years, but has only used it a handful of times. That includes investigations launched in December 2016 by then-state attorney general and current U.S. Senator Kamala Harris. Even police-reform researchers who say these statutes have potential acknowledge they can run into problems when it comes to execution.

Erwin Chemerinsky, dean of the University of California, Irvine, School of Law, said he suspects that political pressures and ambitions deter California attorneys general from exercising their authority more frequently. University of Virginia law professor Rachel Harmon suggested state funding might also present a barrier. “I don’t think mirroring the federal statute, section 14141, is likely to be the most successful state reform effort,” Harmon said, referring to the order granted by Clinton’s 1994 crime bill. “It took the federal government a long time to get that train rolling, and I think it’s very unlikely that the resources or expertise exist in most states to engage in a similarly effective effort.”

Another way for state lawmakers to potentially deter misconduct is through the issuance of professional police licenses. Much like certifications for health-care professionals or lawyers, these licenses can be revoked and prevent police from getting law-enforcement jobs in the state again. This is an area where California lags behind. It is one of about five states without such a mechanism to use after a serious offense. As a result, police chiefs in these states can have complete discretion over the hiring and firing of officers. In an interview last month, Roger Goldman, a law professor emeritus at Saint Louis University in Missouri, told me chiefs rarely exercise their authority to let officers go.

That can have wide-ranging implications for public safety. Sometimes employers hire an officer with a record of misconduct because they simply don’t have access to his or her work history. But other times, Goldman said, departments know a prospective hire’s troubled background, but may hire the officer anyway to reduce training expenses.

Goldman argues that all states need a strong licensing system, but that plan faces its own set of challenges. A critical problem is data—or lack thereof. It’s a multilayered issue involving both individual departments and their broader communities. For example, Frontline has reported that black and Latino communities are less likely to report officer misconduct due to fear that they won’t be believed or may face retaliation. Lawyers and police officials may also keep quiet about officer improprieties to reduce their liability.

Without thoroughly reporting and tracking misconduct, the state law-enforcement training and standards boards tasked with overseeing certifications cannot accurately assess which officers should be considered for decertification. Officers can then quietly resign and potentially find another law-enforcement job. This problem is even worse in states like California that have strict laws preventing the public release of records on police misconduct and the outcomes of internal investigations, said Peter Bibring, director of police practices for the American Civil Liberties Union of California.

Ultimately, state governments have wide-ranging authority to adopt measures for reform. So do cities, though at a more micro level. The key is whether these jurisdictions deem changes necessary on their own, or if they’d only take them under pressure from the federal government.