The Washington Post has an excellent piece on an Arizona milk producer treated unfairly by the federal government's regulatory regime for milk. Briefly, he was initally able to avoid the regime entirely by bottling milk from his own cows, thus allowing him to sell much more cheaply than his competitors who participated in the regime. Not surprisingly, his competitors didn't like this, and eventually succeeded in lobbying Congress to enact legislation forcing him to be part of the regime. It's a great illustration of how government can be used work on behalf of the powerful against the weak: Big producers win, while smaller producers and consumers lose.
He has has now brought suit to have the legislation declared unconstitutional as a bill of attainder. More background here and here.