"Ignorance of the law is no excuse.”

If there is one law-related idea that even lay people are aware of, I would guess this is it.

And that is why I was so surprised at the U.S. Supreme Court’s decision in Heien v. North Carolina four years ago. 135 S.Ct. 530 (2014).

The case concerned an officer in a patrol car who noticed a vehicle with a broken right rear brake light. Believing this to be a violation of North Carolina law, the officer pulled over the car. Nicholas Heien, the driver, subsequently consented to a search of the vehicle that uncovered contraband.

On appeal, the North Carolina Supreme Court noted that the statute in question mandated that a car must be “equipped with a stop lamp.” It interpreted the statute to mean that it is only a violation if both lights are broken. Therefore, Heien had not violated North Carolina law.

But the court went on to hold that because the officer’s mistake of law was reasonable, the stop itself was not a violation of the Fourth Amendment. Rejecting the majority of federal circuits that had considered the issue, the state court held that an officer’s actions can be proper under the Fourth Amendment not only if they are predicated on reasonable mistakes of fact, but also on reasonable mistakes of law.

The U.S. Supreme Court agreed, holding that all the Fourth Amendment ever requires is reasonableness on the part of the police. The court noted that in the past it had held that searches and seizures based on mistakes of fact could be reasonable. And here it acknowledged that “Reasonable men make mistakes of law, too.”

Dissenting, Justice Sonia M. Sotomayor contended that this was an unwarranted expansion of police power. Now, she complained, an officer’s actions will be found proper under the Fourth Amendment so long as he can attach to a reasonable view of facts “some reasonable legal interpretation (or misinterpretation) that suggests a law has been violated.”

I thought of Sotomayor’s dissent when I saw the 1st District Appellate Court’s recent decision in In re Maurice J., 107 N.E.3d 982. Here the police officer saw the driver avoid a speed bump by driving toward the curb with one wheel on the speed bump and one wheel on the level part of the street.

The officer considered this to be a violation of Section 9-8-010(c) of the Chicago Municipal Code which makes it unlawful for a driver to avoid a traffic control device by driving “upon or through any private property, alley or traffic island.” Here the prosecution argued that the officer could have reasonably, albeit mistakenly, believed that a speed bump is similar to a traffic island.

The 1st District curtly replied “We categorically disagree.” In holding for the defense, the court concluded “The case before us does not present an officer’s misunderstanding of the law: It presents an officer’s failure to know the law.”

Heien has the potential of being a decision with far-reaching impact. Therefore, Illinois defense attorneys should recognize Maurice J. as important precedent for setting some limits on a troubling U.S. Supreme Court ruling. “Ignorance of the law is no excuse” applies to the public; it should also apply to the police.

On a personal note, at the end of this month I will be retiring after 36 years of teaching at The John Marshall Law School. Although I certainly hope to contribute occasional Law Bulletin pieces in the future, I will no longer be writing this as a monthly column.

In 1994, the Daily Law Bulletin published an article I had written. The next month I submitted another that was also published. This somehow turned into a monthly habit, and during the last 24 years I have written more than 250 columns. I am very grateful to the Law Bulletin for providing me with this exceptional opportunity.

There is a tendency in all academic fields for professors to write only for an audience of fellow professors. In reaction to that, I always viewed this column as an opportunity to bridge the gap between legal academia and the lawyers and judges who work in the trenches.

Practitioners obviously do not have the time to read every criminal appellate decision, not to mention law review articles. I have tried over the years to bring to your attention an article or case that busy lawyers and judges may have missed.

I also viewed this column as an opportunity to give serious attention to Illinois state appellate decisions. I think law professors in general spend far too much time dissecting a handful of U.S. Supreme Court cases and far too little time analyzing state and lower federal appellate decisions.

I have always appreciated the enormous effort all judges expend on their work. I have tried to highlight some of the first-rate work produced by the Illinois Appellate Court and Illinois Supreme Court. At the same time, I have not shied away from criticizing decisions from those courts that I believed deserved criticism. Regardless, I continue to have enormous respect for the hard work performed by so many lawyers and judges in the criminal justice system in Illinois.

It is a cliche when writers close with the Dickensian “best of times, worst of times” observation. But I believe that one of the reasons so many erroneously believe we are in the “worst of times” is because we are finally opening our eyes to problems that were politely ignored for far too long.

I am just completing a three-year appointment serving on the Illinois Torture Inquiry and Relief Commission. If someone had told me at the beginning of my career that the state of Illinois would ever officially acknowledge that there could be “torture” performed by police officers, I would not have believed it.

The innocent people discovered to have been on death row, the announcement of yet another prisoner being exonerated, the cases brought to light by Black Lives Matter it is important to understand that you cannot begin to solve a problem unless you first acknowledge that you have one.

Achieving justice is a journey that never ends. To all of you working to improve our necessary, but flawed, system thank you.