President Trump spent much of his campaign mouthing “tough on crime” platitudes and a portion of his inaugural address implying that crime was rising. (In fact, it’s near 40-year lows.) Well, two years in office have made a big difference. Trump proved how much his ideas have changed and evolved for the better when his loud public support pushed the First Step Act, a major set of criminal justice reforms, across the finish line late last year. The law is important to recognize and so is the way that Trump and his administration learned — and grew — in office.

Quite simply, the First Step Act is the most significant criminal justice reform in of the past 20 years. While it retains the core practices that brought down America’s crime rate from the highs of the early 1990s, it also tempers them with compassion to make it easier for people who commit crimes to get a second chance. It retroactively eases the powder/crack disparity — already eliminated for offenses committed after 2010 — that often had the impact of punishing black drug dealers more severely than whites, creates an expanded “safety valve” to allow judges to shorten sentences for deserving people and increases opportunities for both “good time” and “earned time” for current inmates. Punishments for the most serious criminals will remain appropriately harsh and rehabilitative programs will only “count” if they actually work. This should still punish the worst of the worst effectively but, at the same time, will allow more resources to be devoted to helping those who need it.

But the directional change remains of enormous importance. The net impact of the First Step Act should be a modest but sustained continuation in a decline in the number of federal inmates (Congress, of course, can’t directly change state laws that define most crimes) that started around 2012.

And Trump’s personal support proved absolutely vital in passing the First Step Act. While the law — tacitly supported but not strongly pushed for by the administration — passed the House of Representatives with bipartisan support in the spring of 2018, doubts among many Senate Republicans made it seem unlikely it would come to the floor. Just a few weeks before passage, indeed, Senate Majority Leader Mitch McConnell indicated that he probably wouldn’t bring the bill to the floor. It took Trump’s explicit Nov. 14 endorsement of the law to push it before the Senate and, eventually, into law.

As big an accomplishment as the law is — it’s the first major bipartisan piece of legislation passed by this administration — it’s at least as significant for the way that it shows Trump embracing conservative principles. Russell Kirk, the father of modern American conservatism, said that conservatives were “sustained by a body of sentiments, rather than by a system of ideological dogmata.”

In other words, while holding fast to certain core principles, conservatism did — and must — change with the times in the specific policies it endorses. Indeed, as Kirk wrote, “the conservative is not opposed to social improvement.” Policies appropriate to a nation with a much higher crime rate no longer make sense and, in the current context, may actually do more harm than good.

Donald Trump’s actions, of course, will never satisfy his political opponents and, in even the First Step Act is a far-from-perfect piece of legislation. But it’s an important law, a significant accomplishment and a sign that President Trump has truly grown in office.

Eli Lehrer is president of the R Street Institute, a nonprofit group working to advocate for limited government.