The U.S. patent system — almost as old as the Constitution — has helped make the United States a worldwide leader in science and technology. Patent laws have helped spur innovations that have revolutionized medicine and transformed transportation, communication and many other aspects of daily life. Today, the U.S. Patent and Trademark Office (PTO) issues about 300,000 patents to inventors each year. But critics, including the high-tech and some other powerful industries, say that the PTO is now issuing too many dubious patents and that some patent holders are engaging in abusive litigation that actually hampers innovation. The House of Representatives passed a broad measure aimed at curbing litigation by so-called “patent trolls” in 2013, but it died in the Senate. Now, the bill is back, with some bipartisan support, but it faces questions from some Democrats and from the pharmaceutical, biotech and venture capital industries. In addition, some experts say recent court decisions and changes at the PTO may make the bill's provisions unnecessary.