The basic rule of law is that a warrantless entry by police into a private home is presumed unreasonable. However, there are exceptions to this basic rule. For example, officers may enter a home without a warrant if a resident gives voluntary consent. But consent, without more, does not give an officer permission to search the entire residence or objects within the residence. Further, whether or not a person really consented is often debatable. Another exception is when an officer has probable cause to believe that exigent circumstances exist (immediate action is needed). Such an officer may enter without a warrant to provide aid to someone; to protect officers from persons whom they reasonably believe to be present, armed, and dangerous; or to prevent the destruction of evidence or contraband. Another exception is when an officer who is in a lawful position sees criminal contraband in plain view inside the home. All these issues can be addressed with a motion to suppress filed by the attorney of a person charged. A winning motion can be the end of the criminal case!
The short answer to that question is NO. However, everyone knows that cars do get searched when people are stopped for traffic violations. There are numerous ways officers can justify a search of a vehicle if they make up their minds to search it. Almost every traffic violation in Texas is an arrestable offense. Once you are arrested, the officer still cannot search your car unless the officer believes you can access your car (you will typically be in the patrol car in handcuffs), or the officer believes there is evidence of the offense for which you were arrested in your car. If these justifications fail, there is the dependable "inventory search" when your car has to be towed. And if you are not arrested for the traffic violation, there is always the "odor of marijuana" inside the vehicle that gives the officer probable cause to search. This one is fail-safe because, if there really is marijuana in the car, the officer can point to it as proof that he smelled it. If there is no marijuana, the officer can make other excuses. You need to have the legality of any car search thoroughly evaluated by a lawyer.
If you are someone who believes you and a significant other are Common Law married, YOUR RIGHTS MAY NOT BE PROTECTED!