> 90% is about right if the number of false convictions is acceptably low. 90% is a terrible number if it should contain a large number of false convictions.
Sure. But you implied above that a 90% conviction rate warrants more scrutiny than a 75% conviction rate. To the contrary, a 90% conviction rate may be indicative of a fair process. A 75% conviction rate is definitely indicative of an unfair process.
Obviously you still need to scrutinize the rate of false convictions. But that's true regardless of the conviction rate. Indeed, a low conviction rate suggests that the government is bringing marginal cases and trying to make things "stick" which increases the risk of false convictions.
> Some will claim this is efficiency but I don't really feel comfortable with an 'efficient' process that places large numbers of people in lock-up.
The U.S. has a large number of people in prison because it imposes long prison sentences for some very common and easy-to-prove things: drug sales, auto theft, assault, firearms. If you take a random sampling of federal convictions, you'll see that almost always there is a laundry list of physical evidence of guilt. The government doesn't bring marginal cases.
The solution to the prison problem is not to force all these clear-cut cases to go to trial. It's to stop imposing 20-year prison sentences for people selling a few pills of Oxycontin, or stop putting felons back in prison for 10 years just for having a gun.