I can't cite the case law off of the top of my head, and I am not the person that you are requesting that of, but I might have something to add here.
There is a case from SCOTUS that illustrates the problem with consent. As a key, it does not have to be the consent of the person occupying the location (it can be given by one with ownership or possessory interest). Secondarily, if two people live in an apartment and one consents and one does not, the police can search over the objections of the non-consenter. Similarly, I believe you will find that there is case law that illustrates that police can get consent from either the legal occupier, OR the owner of the property, OR someone they believe has the authority to consent to the search. Of course, these evaluations are a bit tricky and fact intensive.
In this specific case that I am referencing but cannot remember the name, the police wanted to search a suspected drug leader's apartment, they found his ex girlfriend across town. She still had a key. The police asked if they could search the apartment, and as the ex girlfriend was a little upset at the ex boyfriend, she consented, took them to the apartment and let them in. The court found that the search did not violate the 4th amendment rights of the defendant for a search without a warrant as the police reasonably believed the ex girlfriend had the authority to consent to a search even though she was never legally an owner, and had only stayed with the defendant occasionally. The court, in that case, looked to the subjective understanding of the police. That, to me, is a very scary standard to apply.
There is a huge difference between the academic interpretation of the 4th amendment and the practical application of the 4th amendment. The 4th amendment doesn't physically bar the government from kicking open your door without a warrant, rousing you from your bed at the wrong end of an AR-15, handcuffing you and putting you int he back of a squad car while they ransack your house. What the 4th amendment does provide is some back-end protections from the fruits of that search, if any, against the charges, if any, that they might level after your constitutional rights have been trampled. Yes, you might have some false arrest charges, or some civil rights violations charges, but few people have the time or money to pursue those ends and none of that physically stopped the invasion of your property.
Finally, and of some importance here, is that if the police can seize any illegal items that are in plain site as long as they are at that location legally. So it is very likely that if the police come to your door and knock because they got a noise complaint, or something happened to your car and they wanted to notify you, and you open the door to reveal stacks of cocaine, or pot, or just empty beer cans when you are under-age...you are likely not getting any of that thrown out on 4th amendment grounds, especially when you admit that you have been doing that very illegal activity.