That's a nice policy on paper, but if the actual police training and police department culture aren't changed to effectuate it, such a policy isn't worth the paper it's printed on. Research has shown time and time again people have a strong basic tendency to conform to group pressure and defer to seniority and experience. This requires active training to combat. This means that: A) both new recruits and veterans have to be specifically trained to speak up against (possible) violations, even those committed by higher ranking/ more experienced officers, B) the senior officers must be willing to listen to/ be corrected by (potentially) much less experienced / lower ranking officers, C) the police department culture supports, rather than ostracizes, officers speaking up against colleagues crossing the line.
It is obvious that none of these preconditions were present at the MPD and in fact the opposite was happening: A) Officers, both new and veteran, apparently received no training in crew resource management. B) a rigid command structure where people of lesser rank/experience were expected to defer to those with a higher rank and more experience C) a toxic department culture where officers who crossed the thin blue line were ostracized. No wonder the policy was a complete and abject failure.
Tl:dr: It's nice to write a policy and expect people to follow it, mr. Arradondo, but proper crew resource management requires constant active training and real culture change, and it seems that the MPD simply neglected to implement these.