The question is framed INCORRECTLY. It is only necessary to ask for consent to search if the officers do NOT have a search warrant. In that instance, asking such permission would constitute a legal search and any illegal items they might find would be legally admissible in court. When they are armed WITH a search warrant, unless the officers simply feel like being polite (which we hope they always are) it is NOT required or necessary to ask permission of anyone to conduct the search.
In general, you do not need a search warrant when conducting a search with the voluntary consent of the person being searched.
There is no consent needed from anybody when there is a valid search warrant in play. The court gives the police the right to search by granting the search warrant.
Yes, police generally need to show a search warrant before conducting a search, unless there are specific circumstances that allow for a search without a warrant, such as consent or exigent circumstances.
With a Warrant, consent, or exigent circumstances
Yes. Enforcement officers do not need a search warrant in a variety of instances. If there is consent to a search, you do not need a warrant. If something is in plain view, you do not need a warrant. Also, warrants are not needed in emergency situations when the public safety is in danger.
NO, it isn't. A search warrant limits the scope of a search. Once you have consented to a search, you have placed yourself outside the protections of the fourth amendment! There is no longer any requirements of reasonability and you will likely be prevented from supressing any resulting evidence later on. NEVER consent to a search!
Your consent, or a warrant.
The question is too broad to be answered with any specifics. The authority serving the warrant is constrained by whatever wording is contained in the warrant.
In general, police can search your trunk without a warrant or probable cause if they have your consent or if they believe there is evidence of a crime in the trunk.
The above question is actually a true statement.
Only a legal occupant of a residence, or an owner or employee of a business can consent to a warrantless search of the premises - UNLESS - the search involves the "fresh" or "hot" pursuit of a wanted subject - then, no consent is needed to enter.
Plain view, exigent circumstances, search with consent.