I would propose specific laws that required police, DAs and others to hold those who commit errors in the collection of evidence as negligent, with ranges of penalties depending on how aggregious the error was and how high-up the knowledge and approval of the error went, from suspensions, with and without pay, dismissals, loss of pensions, permanent disability to ever again work in law enforcement and disbarment for those in the legal profession.
Root out the violators, keep the evidence.
And I would propose a law saying that there shall not be more than 6" of rain on Sundays, and my law would have about as much effect as yours.