In Louisiana, the police can generally search a car without a warrant under certain circumstances, although there are exceptions and specific situations that may require a warrant. The key factors that determine whether a warrant is necessary for a car search in Louisiana include:

1. Consent: If the driver or owner of the vehicle gives voluntary and informed consent to the search, the police can conduct the search without a warrant.

2. Probable cause: If the police have probable cause to believe that the vehicle contains evidence of a crime or contraband, they can conduct a warrantless search. Probable cause means having reasonable grounds to believe that a crime has been committed or that evidence of a crime or contraband is present in the vehicle.

3. Exigent circumstances: If there are urgent circumstances that require immediate action, such as the imminent destruction of evidence, the police may search a vehicle without a warrant. The specific circumstances must be evaluated on a case-by-case basis.

It's important to note that while these are general guidelines, the interpretation and application of the law can vary, and there may be additional state or federal laws that impact vehicle searches in specific situations. If you have a specific legal concern or believe your rights have been violated, it is advisable to consult with a lawyer who is knowledgeable in Louisiana law.