Minimum penalties and prosecutorial power [Updated]

A reasonable critique of minimum sentencing laws, and consequently of three-strikes legislation: they let prosecutors force plea bargains for offences without such minima because accused parties fear erroneous conviction and high penalties. Here's the New York Times (HT: all over Twitter)

“We now have an incredible concentration of power in the hands of prosecutors,” said Richard E. Myers II, a former assistant United States attorney who is now an associate professor of law at the University of North Carolina. He said that so much influence now resides with prosecutors that “in the wrong hands, the criminal justice system can be held hostage.” One crucial, if unheralded, effect of this shift is now coming into sharper view, according to academics who study the issue. Growing prosecutorial power is a significant reason that the percentage of felony cases that go to trial has dropped sharply in many places. Plea bargains have been common for more than a century, but lately they have begun to put the trial system out of business in some courtrooms. By one count, fewer than one in 40 felony cases now make it to trial, according to data from nine states that have published such records since the 1970s, when the ratio was about one in 12. The decline has been even steeper in federal district courts.

I wonder whether this effect has contaminated the studies on California's Three Strikes law. Recall that we've seen a big decline in strikeable offences and a smaller increase in non-strikeable offences. The argument has been that some of the decline in strikeable offences has been due to criminals substituting into offences carrying lesser potential sentence. Some of that substitution could just be the exercise of prosecutorial discretion in coercing a guilty plea on a non-strikeable offence where the accused fears the risk of taking a potential strikeable charge to trial. The effect can't be that large though: if it were all that kind of prosecutorial substitution, we'd expect the increase in non-strikeable offences to be larger relative to the decline in strikeable offences. UPDATE: Iyengar's work uses arrest data rather than conviction, and Shepherd's is all on crime rates. So unlikely to be a problem. See comments below, thanks to Lemmus!

I don't know the extent to which plea bargain is used in New Zealand. But this will be something to watch for as our three-strikes legislation becomes binding on more accused.

Previously:

• Is three strikes working?
• Marginal deterrence for the incarcerated
• A good strike
• Against the death penalty
• In favour of flogging