Continuation Patents and Litigation

Continuations allow patentees in the United States to modify the scope of previous patents, leading to concerns about patent disputes generated by changes in patent boundaries. I show that continuations are litigated more often than original patents, even after controlling for patent and invention characteristics. I also exploit the pre-grant publication of patent applications and the timing of continuation grant to show that continuation grant increases litigation. The effect is stronger when the textual distance between the claims of a continuation and those of its original patent is greater, suggesting larger changes in scope lead to more disputes.