You say that "it's not any 'Blackstone bias' that ends up protecting the criminal, it's a result of the state's agent failing to follow the law." However, you're giving me a legal judgment which has Blackstone as its premise..
Reasonable minds, not trying to play lawyer, would not reach the same decision as you have. It's a matter of weighing two factors. Which is the most important?
-- The violation of the property rights of the killer-husband or...
-- the protection of innocent citizens and justice for the murdered wife
The detective should receive a slap on the wrist for his violation. However, it can't be ignored that he acted in pursuit of his primary duty to protect the innocent public. Absent the Blackstone bias, it's an easy call.
You're asking the wrong questions. It should be, which is more important:
- Justice for the murdered wife or...
- Protection of EVERY SINGLE American citizens' right not to have their property rights violated by the state.
Because the laws that are in place that REQUIRE agents of the state to have a VALID search warrant aren't designed to protect criminals, they are designed to protect innocent citizens from abuses by the state.
So lets take a close look at what would happen if we indeed decided that when an agent of the state violates a citizen's constitutional right to not be subjected to unreasonable searches gets a 'slap on the wrist', while the state gets to go ahead and use whatever incriminating evidence they might discover during this illegal search.
How many cops are going to be more than willing to accept this mere 'slap on the wrist' based on nothing more than the fact that if you randomly search most people's homes you'll find SOME violation of the law. After all, in the society we live in there are many states where finding a mere quarter ounce of pot in someone's dresser drawer would justify the illegal search. How many members of the justice system would in fact encourage police officers to illegally search whenever possible - since after all doing so only results in a slap on the wrist, which is nothing that actually threatens their job or freedoms - just to get the arrest numbers up? Within the department being a cop who has a lot of slaps on the wrist in his record would actually be held in high esteem. After all, all cops know that if they can find more reasons to make arrests during routine traffic stops the more praise they get for doing a good job. We already know that cops getting 'reprimands' on their records for police brutality don't worry about it, since the state does everything in their power to keep such records from the public and only dismiss them if their violations are caught on tape and end up getting heavily publicized.
What you're suggesting wouldn't actually be 'harder on crime'. It would be 'harder' on criminals of the state, while being considerably 'softer' on crimes committed by the state. That's a trade-ff you can make, but it's not something I would advocate for... nor would the founding fathers. It's true that if we simply allowed the state to search any citizen's property at any time and for any reason that we WOULD end up getting justice for more victims of crime in society, but at what cost? You're basically making the argument of the police state, which of course always claims that it's purpose to to keep citizens safe. The idea is that IF you're a law abiding citizen THEN you don't need protections against unreasonable searches... since such 'protections' ONLY protect criminals.
The reason we have such protections is because most people have LESS fear of any individual criminal than they do of agents of the state having unchecked power over their lives. The laws we have that restrict the state's power are just as important if not more important than the laws we have that restrict citizen's criminal activities. Just ask anyone who's ever lived in a totalitarian state.