When making traffic stops, police officers must follow and abide by certain procedural rules and laws. These laws exist to prevent officers from making indiscriminate and at-will traffic stops and help ensure that an individual's Fourth Amendment rights are not violated.
The Fourth Amendment of the U.S. Constitution protects individuals from "unreasonable searches and seizures of property by the government." While the purpose of the Fourth Amendment is clear, when it comes to traffic stops there may be questions about whether or not a police officer's actions were in violation of the Fourth Amendment.
A recent United States Supreme Court decision held that when officers make a reasonable mistake of law, the stop will still be allowed and no evidence will be suppressed. In that case, the officer (from NC) erroneously believed that TWO brake lights were required when the actually only requred one. The court allowed the stop, holding that the mistake was reasobable and the attorney's efforts to suppress the evidence (and dismiss the case) were not allowed.