Your police training will include information about the workings of the American judicial system. It’s important for you to be familiar with courtroom protocols and to understand how judicial decisions are made. During your training you will probably spend a day observing how the courts function. Later, as an active police officer, you may be returning to court numerous times to testify about your dealings with offenders.

It’s important to know that a judge may dismiss a case on procedural grounds even when a suspect is obviously guilty. “Procedural grounds” refers to numerous rules limit the way that crime is punished in the United States.

Officers who are eager to apprehend criminals sometimes feel frustrated by these rules—for search warrants, for example. But the principle of fairness is deeply cherished by Americans, and everyone—including law enforcement—is obliged to follow rules that concerning guilt, innocence, privacy, and punishment.

Sometimes there are disagreements about what a law means or how it applies in a particular situation. When this happens, the district attorney (a local official in charge of prosecutions) may decide to ask a higher court to review the case—a process called an appeal. Eventually the case may reach the Supreme Court in Washington DC. As a result, a decision at the highest court in the land can affect policing in a small town many miles away from Washington DC.

Two 2013 Supreme Court cases about K-9 officers illustrate the kinds of issues that can arise and how they’re decided. In the first case, Florida v. Harris, there was disagreement about a trained police canine, Aldo, that had detected drugs during a vehicle search.

Although Aldo was trained to do drug searches, paperwork for his certification and training was incomplete. Lower courts threw out the results of the search, but the Supreme Court unanimously decided in favor of Aldo and his search. The problem with the early decisions, the Court said, was that they were trying to set a rigid standard—a checklist—for probable cause, which should be a broadly defined concept.

That same day the Supreme Court decided another case, also in Florida and also involving a canine. Police had a tip that a citizen was growing marijuana in his home. A drug-sniffing canine went onto the citizen’s front porch and detected marijuana. Police obtained a search warrant, went into the house, and found marijuana plants. An appellate court declared the search was legal because a porch is a semi-public place, but the Supreme Court declared the search illegal.

Not all cases are decided in favor of law enforcement, of course. Whatever the decision, many of these cases have far-reaching implications because they provide answers to practical questions about police procedures. In the two Florida cases, officers learned that a) probable cause is a broad idea that can’t be reduced to a checklist and b) a citizen’s front porch is not the same as a room inside of the house.

There are limitations on what the Supreme Court can do. It can deal only with cases that have already been litigated, and the person filing the request for a hearing must have an interest in the outcome. The Supreme Court cannot just read about an issue in the newspaper and make a decision about it.

Every year the Supreme Court chooses to hear a limited number of cases, some involving law enforcement. As a professional police officer, you should take an interest in these cases and make sure you understand how they affect your agency’s policies and procedures.