While police generally need a warrant to search you or your property — during a traffic stop, police only need probable cause to legally search your vehicle. Probable cause means police must have some facts or evidence to believe you’re involved in criminal activity.

In other words, an officer’s hunch without evidence of illegal activity is not enough to legally search your car. Before searching, he must observe something real. Common examples of probable cause include the sight or smell of contraband in plain view or plain smell, or an admission of guilt for a specific crime. The presentation of any of these facts would allow an officer to perform a search and make an arrest.

Be aware that minor traffic violations (e.g. speeding, broken tail-light, or expired registration) are not considered probable cause.

Okay. So how can I keep police from searching my car?

Simply understanding the legal definition of probable cause probably won’t be enough to prepare you for the pressure and confusion of a real police encounter.

Most police are able to exploit a major loophole to the probable cause search requirement. But by following these basic rules, you’ll be better able to prevent police from tricking you into giving up your your constitutional rights. You’ll also improve your odds of driving away safely.

Always Be Calm & Cool

If police flag you down, pull over immediately, turn off your car, and place your hands on the wheel. Police like to see your hands for their own safety — so wait until they request your paperwork before reaching for it. At night, it’s also a good idea to turn on the dome light, so the officer can see you’re not armed.

Always greet policemen and policewomen as “Officer”. For example, you may start off with “Good afternoon, Officer. How’s it going today?” Under no circumstances should you ever talk back, raise your voice, or use profanity with a police officer. Being hostile with police is stupid and dangerous. You can’t win that game.

If the officer writes you a ticket, accept it quietly and never complain. Listen to any instruction on paying the fine or contesting the ticket, and drive away slowly.

Remain Silent: What You Don’t Say Can’t Hurt You

Police may try to get you to admit to having broken a law. For example, an officer may ask, “Do you know how fast you were going?”

You may assert your 5th Amendment protection against self-incrimination by refusing to admit you might have broken a law. As such, the best answer to that and similar questions is “No, Officer.”

Because anything you say can and will be used against you in court, the less you say the better. You also don’t want to announce to police that you know your rights. They’ll take that as a challenge. Just keep quiet and calm.

You Have the Right to Refuse Search Requests

Police may order the driver and any passengers out of the vehicle. If this happens, step out of the car. If they have reasonable suspicion to detain you, police may frisk the outside of your clothing to check for weapons, but only if they have a basis for suspecting you’re armed.

If police detain and frisk you, you have the right to clearly state your refusal to consent to the search. For example, you may say “Officer, I’m not resisting. I do not consent to this search.” But you should only verbally refuse. Never physically resist. Just touching an officer could get you tasered or beaten. You could also get a felony charge for assaulting a police officer.

Whether they frisk you or not, police may ask you a series of questions. They will probably include something like “You don’t mind if I have a look in your car?” Beware of that question: It’s the legal loophole that the officer wants to snare you in. (It might even sound like a command, but it’s technically a request.)

In response to such request, you may politely decline by saying “Officer, I know you’re just doing your job, but I don’t consent to searches.” Some officers may use their authority to make you feel obligated to prove your innocence by asking “What do you have to hide?” Don’t fall for such tricks. If necessary, repeat your refusal.

Remember: The 4th Amendment protects your right to refuse search requests, but it doesn’t require police to tell you about your right to refuse. In fact, consenting to searches automatically makes them legal in the eyes of the law. So if you’re pulled over, don’t try to figure out whether or not the officer has probable cause to legally search you. You always have the right to refuse searches.

Refusing a search request is not an admission of guilt and does not give the officer the legal right to search or detain you. In fact, most avoidable police searches don’t occur because police have probable cause. They occur because people get tricked or intimidated into consenting to search requests.

If police search your car and find illegal items despite your refusal, your lawyer can file a motion to suppress — or throw out — the evidence in court. If the judge agrees that the officer’s search violated the 4th Amendment’s probable cause requirements, she’ll grant the motion. Unless the prosecution has other evidence, your charges would be dismissed.

Determine if You’re Free to Go

Unless you’re detained or arrested, you may terminate the encounter anytime. But don’t wait for the officer to dismiss you. Ask if you’re free to go.

For example, if an officer threatens to call in a K-9 unit if you refuse a search, you should ask “Officer, are you detaining me, or am I free to go?

Not only can this line can help withdraw you from an encounter, it also deflects any of the officer’s probing questions or threats. So if an officer says “If you cooperate with me, everything will go easy for you.” You may respond by saying either “Officer, I don’t consent to any searches” or “Officer, am I free to go?”

If the officer lets you leave, do so immediately. If the officer’s answer is unclear, or if he asks additional questions, persist by repeating “Officer, am I free to go?”

Ask for a Lawyer

If you are not free to go, you are being detained. The officer might have some reason to suspect you of a crime, and you may be arrested.

In such a situation, your magic words are “I’m going to remain silent. I would like to see a lawyer.” These magic words are like a legal condom. They’re your best protection if you’re under arrest.

Never rely on police to inform you of your right to remain silent and see a lawyer. Repeat the magic words as necessary, but say no more. Remember that anything you say can and will be used against you in court.