Too many laws, too many prisoners

Here's The Economist, on a notorious smuggler:

THREE pickup trucks pulled up outside George Norris’s home in Spring, Texas. Six armed police in flak jackets jumped out. Thinking they must have come to the wrong place, Mr Norris opened his front door, and was startled to be shoved against a wall and frisked for weapons. He was forced into a chair for four hours while officers ransacked his house. They pulled out drawers, rifled through papers, dumped things on the floor and eventually loaded 37 boxes of Mr Norris’s possessions onto their pickups. They refused to tell him what he had done wrong. “It wasn’t fun, I can tell you that,” he recalls.

Mr Norris was 65 years old at the time, and a collector of orchids. He eventually discovered that he was suspected of smuggling the flowers into America, an offence under the Convention on International Trade in Endangered Species. This came as a shock. He did indeed import flowers and sell them to other orchid-lovers. And it was true that his suppliers in Latin America were sometimes sloppy about their paperwork. In a shipment of many similar-looking plants, it was rare for each permit to match each orchid precisely.

In March 2004, five months after the raid, Mr Norris was indicted, handcuffed and thrown into a cell with a suspected murderer and two suspected drug-dealers. When told why he was there, “they thought it hilarious.” One asked: “What do you do with these things? Smoke ’em?”

Prosecutors described Mr Norris as the “kingpin” of an international smuggling ring. He was dumbfounded: his annual profits were never more than about $20,000. When prosecutors suggested that he should inform on other smugglers in return for a lighter sentence, he refused, insisting he knew nothing beyond hearsay.

He pleaded innocent. But an undercover federal agent had ordered some orchids from him, a few of which arrived without the correct papers. For this, he was charged with making a false statement to a government official, a federal crime punishable by up to five years in prison. Since he had communicated with his suppliers, he was charged with conspiracy, which also carries a potential five-year term.

The article continues:

Justice is harsher in America than in any other rich country. Between 2.3m and 2.4m Americans are behind bars, roughly one in every 100 adults. If those on parole or probation are included, one adult in 31 is under “correctional” supervision. As a proportion of its total population, America incarcerates five times more people than Britain, nine times more than Germany and 12 times more than Japan. Overcrowding is the norm. Federal prisons house 60% more inmates than they were designed for. State lock-ups are only slightly less stuffed.

The system has three big flaws, say criminologists. First, it puts too many people away for too long. Second, it criminalises acts that need not be criminalised. Third, it is unpredictable. Many laws, especially federal ones, are so vaguely written that people cannot easily tell whether they have broken them.

This creates something known as "prosecutorial discretion", in which district attorneys and other politicians can arbitrarily hammer anyone who is currently unpopular. 
Check out "Three Felonies A Day" by Harvey Silvergate if you get a chance. 
If you're curious about who is currently commiting 3 felonies every day, the really long answer is:
You.