Last week, Amazon sent a stark message to highly paid employees thinking about leaving the company for a rival: Do so and we might sue. But Amazon is only too happy to hire away employees from those same rivals. 

In recent years, Amazon has poached prominent people from Microsoft, Google, VMware and other companies, and those competitors didn’t respond with lawsuits aimed at preventing their former employees from joining Amazon. But last week, the company’s cloud computing unit, Amazon Web Services, filed a lawsuit against Brian Hall, a high-profile former marketing executive, to prevent him from going to work at Google’s cloud computing division. The lawsuit has reignited the controversy over noncompete agreements, which are considered unenforceable in some states.