IMO the "most effective way to eliminate bad patents would be to" set patent lifetimes that are industry/field specific -- you get a number of years of patent p

IMO the "most effective way to eliminate bad patents would be to" set patent lifetimes that are industry/field specific -- you get a number of years of patent protection that should be enough to yield a positive ROI in that industry/field. So pharma might get 20 years like they do today, hardware might get 12, software might get 8, and cryptography might get 5 (no one ever turns much of a profit with cryptography patents -- the entire industry avoids them like the plague). This will greatly discourage patent trolls because they won't have enough years to shake people down. But it won't discourage legitimate patent owners, and it will encourage continuous innovation (so that products can keep some patent protection all the time).