The bulb suddenly is flickering for many of America’s most innovative businesses — life sciences companies, pharmaceutical developers, software developers and a wide range of manufacturers. It’s especially troubling because we depend on these businesses to light the way for growth, ingenuity and global competitiveness. The threat to those imperatives is a change to a tax law originally enacted nearly 70 years ago that provided a key incentive for American innovation and helped solidify the United States’ position at the heart of the global economy. Companies can no longer immediately deduct all their research and development expenses from the income...