People can be difficult as Cracked pointed out in an article describing laws that contributed to the very problem they were trying to solve:

• In the days of British controlled India, Delhi had a snake problem and so the governor offered a bounty on snakes. Ever enterprising, the residents of the city bred their own snakes and then killed them for the bounty. By the time the bounty program had ended the number of snakes had massively increased.
• When Mexico City tried to control pollution levels by preventing cars with certain license plate numbers from driving on certain days of the week, Mexicans responded by buying an additional car with a license plate ending in a different number to circumvent the ban. The additional cars were cheap high polluting cars…contributing to Mexico’s pollution problems.
• Gun buyback programs increase the amount of guns since buyers know that if they regret their purchase they can easily return it at the next buyback…or perhaps sell their current gun to upgrade to a better one
• Fishing quotas in the European Union led to fisherman sorting through their catch to pick only the best fish. To stay within the limits of the quota the rest of the (dead) fish were thrown back into the ocean…polluting it, and killing more fish.

There’s more on the full list, and of course a summary like the one above can’t reproduce the wit and humour of the article. You should read it here.

Source: Cracked