A great example is copper and other scrap metal theft. In 2007, then House Criminal Jurisprudence Committee Chairman Aaron Peña carried legislation that boosted penalties of any amount of copper and other industrial metals to a state jail felony, no matter what its value, at the behest of construction and utility companies who cited growing metal thefts to sell for scrap. Since then, the amount of such theft has continued to rise unabated, seemingly driven almost entirely by the price of copper and other metals and entirely undeterred by the new felony status of stealing a few dollars worth of wire. Apparently the people willing to risk their lives pulling wire out electrical boxes didn't read their pocket copies of the penal code to pick up on the increased penalties (surprise, surprise!). As evidence, check out this recent report on the subject from KHOU-TV out of Houston titled "Copper Theft Plaguing Local Homebuilders":
So the new felony for stealing any amount of copper had no apparent effect at all. Why? Because the problem wasn't that the penalty was too low, but that police are using ineffective tactics. Targeting homeless copper thieves and locking them up is fruitless. Clearance rates for this crime are extremely low, and there's always another scrap metal thief where the last one came from, and will be as long as there are desperate people and a robust market for the stolen property. This is the wrong tactic: Instead, police should be targeting the handful of scrap metal dealers who provide the market for criminals of this sort in undercover stings. Then, if there's no place to sell their stolen wares, the thieves will move onto something else.
Many crimes for which legislators seek enhancements year after year - scrap metal theft, graffiti, car burglaries, etc. - are offenses with extremely low clearance rates. They're not solved very often, so on the rare occasions they are, authorities seek the chance to show the public how "tuff" they are. But the smart thing to do in such instances is focus on strategies that increase clearance rates so offenders are more likely to be caught, or in cases like metal theft, find ways to disrupt the black market that get more bang for the buck given scarce criminal justice resources.
Bottom line: The copper theft example shows that making things that are already illegal more illegal usually isn't a deterrent to people who're willing to do illegal things. Somehow, though, whenever the next problem rolls around, legislators seem to forget that lesson and reach for the same, tired non-solutions.