If bag means pillow case or sack, what is the difference between a bag and "no-bag"?
If a bag means a steel suitcase with combination lock with lettering indicating that it belongs to someone definitely not you, then maybe the police need a warrant.
However, if a crime occurs and they take your automobile, they will need to inventory the contents and a steel suitcase would be part of the contents, and the owner might have a chance to ask for a TRO / suppression before a warrant issued for its search.
That pretty much colors in a continuum between "paper bag" and steel container in trunk, with all other facts and circumstances falling in between.
In addition, there is the question of how you came to be pulled over and whether that was legitimate, and which prefaces the question of "what sort of container it was within".
Hire an attorney and explore every avenue: (1) propriety of the stop, (2) opportunity to smell, (3) location and type of bag, (4) whether locked, and much much more.
Curt Harrington Patent & Tax Law Attorney Certified Tax Specialist by the California Board of Legal Specialization PATENTAX.COM This communication is general information and not legal advice, and does not create an attorney-client relationship. This communication should not be relied upon as any type of legal advice. Please note that no attorney-client relationship exists between the sender and the recipient of this message in the absence of either (1) a signed fee contract and (2) remission of an agreed-upon retainer. Absent such an agreement and retainer, I am not engaged by you as an attorney, nor is any other member of my law firm.
Technically they are not allowed to search "closed containers" without an exception. Exigent circumstances or a warrant.
If the driver was arrested, the police may go with "inventory search" of the vehicle pending impounding.
I think you should hire a good criminal attorney and fight the "illegal search."
and were you charged with anything? Depending on the full facts here it very well could be that there is a search warrant violation here. Closed containers normally require a search warrant. If you are facing criminal charges based on this fact pattern you should do a free consultation with an attorney.