The Fourth Amendment to the U.S. Constitution provides some of the most important protections in criminal defense. Among other things, it protects the people from “unreasonable” searches and seizures. This means that the police generally need a warrant to arrest a person or search their property, unless some exception applies.
However, there are a lot of exceptions. In fact, most arrests and searches take place without a warrant. For instance, if an officer sees a driver run a red light, the officer can pull over the driver and issue a ticket. If, during this traffic stop, the officer encounters further evidence of a crime — for instance, if the officer smells alcohol on the driver’s breath — then the officer may require the driver to step out of the vehicle and take a roadside sobriety test. This can help the officer gather more evidence justifying an arrest.
The “plain view” exception
Similarly, the “plain view” exception applies when an officer sees evidence of a crime in plain view while the officer is somewhere they have a right to be. For instance, if an officer is walking down a city sidewalk and happens to see a person who appears to be using illegal drugs in a parked car, the officer probably does not need a warrant to search the car.
While the two examples above seem relatively straightforward, many cases are not so clear. If the police overstep their authority and conduct an unreasonable search or seizure, they have violated a person’s constitutional rights. If that is the case, the defendant may be able to convince the court to suppress the evidence taken from the unconstitutional arrest or search. Without this evidence, the prosecution’s case can fall apart, and the defendant can beat the charges.