Pharmaceutical patent challenges--time for reassessment?

For nearly 15 years after the passage of the Hatch-Waxman Act in 1984, generics drug companies took little advantage of its provisions, which provided financial incentives to them for challenging the patents of branded pharmaceutical products. However, during the past 3-5 years, generics manufacturers have dramatically increased the number of patent challenges. Although these challenges can certainly benefit consumers and payers, the number of challenges puts many innovator companies at risk, which they argue is detrimental to future R&D spending. If many of the challenges are successful, then the increase in challenges could in turn be detrimental to generics, and the system itself might therefore be due for a re-balance.