This post was first published on July 18, 2014.   After studying citations from patents that were invalidated by US Judges, researchers from the London School of Economics commented, "Patent invalidation has a significant impact on cumulative innovation in the fields of computers and communications, electronics and medical instruments (including biotechnology). We find no such effect in fields involving drugs, chemicals or mechanical technologies." Let us now take a look at why this discrepancy exists. What is patent invalidation?…