Case number 1: Open up, it's the FBI. Not!
Robbers claiming to be FBI agents forced their way into a home in Burbank, California, after midnight. Then they robbed the family of $20,000 cash. Link.
Lessons learned. First, law enforcement shouldn't force their way into a house until after providing authentication that they really are law enforcement officers. An armed homeowner would then know that anyone trying to force their way in without law enforcement authentication is up to no good, and reasonable defensive force would be justified.
Second, $20,000 is a bit much petty cash to have around the house. And maybe the perps knew it was there.
Case number 2: Go free until there's room at the jail.
A prosecutor in Dunkirk, France, named Philippe Muller determined that 150% of capacity is the maximum number of prisoners he will allow in the jail. So he will delay incarcerating new prisoners until there is room for them. Link.
Lesson learned. If incarceration is supposed to be a deterrent to crime. Then non-incarceration would be an incentive. Then again, maybe they are convicting too many people of trivial offenses.