What are the exceptions to the warrant requirement?

We'll do a deep dive into each of these in other cards, but here's a summary of the 7 exceptions to the requirement that the government must first get a warrant before performing a search of someone's body or property:

(1) When there is an emergency or some urgent circumstance, like chasing an armed robber through an apartment building, which may require entering people's homes without first getting a warrant.
(2) The stop and frisk exception, which enables police to stop people under certain conditions and then, if they feel there is a risk of the person they stopped being a threat, search their body or parts of their vehicle for weapons.
(3) Consent. This one is pretty obvious. If a cop knocks on your door and says, "Can I search your house?" and you say, "Yup!" and let them in, they don't need a warrant because you have invited their search.
(4) If police have probable cause to believe that a vehicle contains something criminal, they can search it without first getting a warrant. The rationale for this is because the vehicle can drive off during the time that an officer would need to go get a warrant and return.
(5) If an officer is somewhere they have a legal right to be, and from that position they can see evidence of a crime in plain view, then they can retrieve that evidence without having to get a warrant. For example, if a cop walks by a car on the street and sees an illegal firearm sitting on the passenger seat, they don't need a warrant to enter the vehicle and get the gun.
(6) If criminals talk about crimes so loud that someone can overhear and eavesdrop on those conversations, then no warrant is required to listen. Additionally, though wiretapping a phone line requires a warrant, wiretapping a person does not. In other words, if police place a wire on an informant, and a criminal chooses to confess crimes to that informant, the police don't need a warrant to listen or record from that wire.
(7) A search incident to arrest is a normal search that happens after someone is arrested. No warrant is needed.