The California legislature just made it easier to install graywater systems. That's cool, because the existing standards were so tough that legal systems cost over $2,500.* That's pretty steep compared to the $150 cost of illegal systems.
Can anyone guess how conservation-minded people responded? These do-gooders thought of cost and benefits (yay economics!) and decided to break the law -- at an 8,000 to one rate. Now they needn't fear prison for dumping their sink water in the garden.
Bottom Line: People will break stupid laws. Stupid laws do not only reduce the value of other laws, but they draw legal and enforcement resources away from important laws. (Compare drug laws to laws against violent crime.)
* This article was "community funded" through the spot.us model of bottom-up journalism. Anyone interested in the survival of the fourth estate should check them out (and send a few bucks)