Inventors patent ideas to pre-empt their rivals Companies then must buy rights to the devices ...If a company decides to build a product based on his idea, it might have to buy the patent from him, pay him a licensing fee or face him in court. It's part of a legal tactic called "offensive blocking patents" in which businesses or individual entrepreneurs use patents not so much as tools to build new products, but as legal roadblocks or bargaining chips against competitors or corporate giants. Some legal experts, including those representing big corporations, are skeptical of this approach, which...