Since the horrific terrorist attack in Orlando, Florida nearly two weeks ago – the worst terrorist attack on U.S. soil since 9/11 – Congress has been engrossed in a debate about what can be done to prevent something like this from happening again.

In their grief for the victims, and in their concern about the safety of our communities, many Americans have come to the same conclusion: “something must be done.” Unfortunately, many of members of Congress believe that those four words – “something must be done” – give the federal government permission to do whatever it wants.

But the government can’t do whatever it wants, not even at a time of great anxiety and insecurity. In fact, there are several things that the government is expressly prohibited from doing under any circumstances.

The government may not infringe on “the right of the people to keep and bear Arms.” It may not violate the “right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures.” Nor may it deprive any person “of life, liberty, or property, without due process of law.”

These are just a few of the explicit limitations on government action – a few of Americans’ core civil liberties – listed in the Bill of Rights. They are not negotiable. Yet many of the legislative proposals that have emerged in recent days run roughshod over these basic constitutional rights.

One such measure would give law-enforcement agencies power to access Americans’ Internet browsing history and email metadata – which can be analyzed to reveal intimate details about a person’s life – without a warrant, probable cause, or judicial review by a federal court. Another measure, the Terrorist Firearms and Prevention Act, would prohibit individuals on the government’s secret No Fly List or Selectee List from purchasing firearms.

Everyone agrees that terrorists should be prevented from purchasing guns, but this proposal would deny Americans their Second Amendment rights based on a mere suspicion from the FBI that they are engaged in terrorist activity. The denial of a constitutional right should require more proof than a reasonable suspicion – a standard so low that it doesn’t even justify an arrest.

In defending these measures, some proponents have lamented the difficulty of working around the core civil liberties listed in the Bill of Rights. But this is a feature, not a bug, of our constitutional system.

Americans’ constitutional rights are not nuisances that the government must accommodate. Protecting these rights is the reason that government exists. As we continue consideration of these measures next week, we must work to ensure that Congress fulfills this purpose.