Consider the following all-too-common scenario: employee leaks valuable company information to a competitor and is fired. Company then sues the employee for breach of an employment NDA, which applies to “all proprietary information” that the employee received. The confidentiality obligation is evergreen--an all-too common feature of employee NDAs.
Outcome? In a state where employer-mandated non-compete covenants are enforceable if reasonable, a US court has struck down this exact NDA as an unreasonable restraint of trade.