Ten days ago the Supreme Court handed down Hudson v. Michigan, a hotly debated opinion saying in a 5-4 split that courts may still use evidence gathered after police have violated the “knock and announce” rule that is part of our Fourth Amendment search and seizure protection.

Some have bemoaned and some have celebrated what is predicted to be a new wave of conservative civil liberties rulings by the court. However, this case actually illuminates a disagreement among the justices about the remedy when civil liberties are violated.

In terms of defining or clarifying our civil liberties, the case does not begin to approach the level of violation that occurred when President Bush allowed the National Security Agency to wiretap phones without a warrant.

The Fourth Amendment states that searches and seizures by the government must not be “unreasonable.”

Ten years ago the Supreme Court ruled unanimously that the common law “knock and announce” policy should be included in assessing what is and is not unreasonable under the Fourth Amendment. That opinion was not only unanimous, but it was written by Justice Clarence Thomas, who is one of our most ardent “textualist” judges. The fact that even he read “knock and announce” into the Constitution, where it does not actually appear, demonstrated the justices’ commitment to search and seizure protections.

The question in Hudson, however, was this: What should we do when the knock and announce rule is violated?

The defendant wanted the exclusionary rule to apply, which means that evidence obtained after the failure to knock and announce could not be used against him.

The exclusionary rule is much maligned as a “loophole” that can let criminals go free. Since the beginning of the 1900s it has been applied in federal cases where police fail to get a warrant. Supreme Court justices determined that the warrant was the key to protecting the privacy inherent in the search and seizure provision of the Constitution.

The penalty for failure to get a warrant had to be high enough to deter law enforcement from skipping over this requirement. And, in 1961 when the Supreme Court decided that states as well as the federal government should apply the exclusionary rule in cases without warrants, the justices made a sweeping statement that the exclusionary rule was the proper tool whenever the Fourth Amendment was violated.

But, immediately after that ruling was handed down we began to see that the exclusionary rule could not be applied every single time a civil liberty is violated. Because the social consequences of letting the guilty go free are so high, the exclusionary rule had to be a remedy of last resort.

The 1980s were a decade in which the Supreme Court began to define more clearly when the exclusionary rule would be used and when other remedies like civil lawsuits were better tools to deter police from violating the Fourth Amendment.

In Hudson, the majority opinion said that the exclusionary rule was not required by the Constitution when knock and announce was not followed. Instead, wrote Justice Scalia, civil lawsuits could be commenced against police or internal sanctions could be assessed when violations of knock and announce were egregious.

Scalia’s opinion suggested that if evidence indicated that these tools did not serve to be great enough deterrence, the court could revisit the issue. And, the door is always left open to the states to pass legislation that does apply the exclusionary rule if the states deem this to be good policy. Hudson ruled only that the Constitution does not demand the exclusionary rule in cases like this.

Over the course of my legal career I’ve prosecuted offenses and I’ve defended those accused of crimes. I’ve seen the best of what the police and the government can do, and I’ve seen the worst.

I’m committed to civil liberties and I support the exclusionary rule as an appropriate last resort remedy. I’m concerned about the unrestrained power of the government and I know that there will be cases before the court that should worry us.

If the court weakens the exclusionary rule in cases where evidence is gathered without a warrant, we should worry. If the executive branch of government says it can collect evidence without a warrant, we should worry. But, Hudson is not the case that should worry us.