More employers are requiring their new workers to sign "noncompete" agreements, which they say are needed to prevent insiders from taking trade secrets, business relationships or customer data to competing firms when they leave.

But with a more than 60% rise over the past decade in the number of departing employees who are getting sued by their former bosses for breaching the agreements, some worry these clauses are having an unintended damping effect on U.S. entrepreneurship, by preventing people from leaving the corporate world to launch their own businesses, or hire workers when they do.

Take Rami Essaid, for instance. Within a few months of launching an Arlington, Va., startup last year, which protects websites from attacks by automated computer programs, he was sued by his former employer, a large publicly traded computer security firm, saying he had violated a noncompete clause in his previous employment contract. He spent six months negotiating a settlement with his ex-employer. Noncompete agreements, he says, can be a significant impediment to people who aspire to start their own firms because they "limit your ability to grow and tap your networks."

Both large corporations and smaller firms use noncompete agreements. Employers say trade secrets and customer good will can both be put at risk when an employee moves on.

"Employers are always looking to protect their most valuable assets and that includes their workforce, but it also includes things like their trade secrets and their confidential information and customer relationships," says Richard C. Schoenstein, a partner with Satterlee Stephens Burke & Burke LLP. In addition, "a lot of times it's a disincentive to leaving," he adds, noting that employers make a significant investment in employees.