R, an optical surgeon, employs S as the assistant for a term of three years and S agrees not to practice as a surgeon during this period. This contract is

Restraint of trade agreements in employment contracts are void if unreasonable. Here, the restraint is limited in time (3 years) and directly related to protecting the employer's legitimate interest in his assistant's skills during employment. Courts generally uphold reasonable restraints that don't extend beyond the employment term or unreasonably restrict trade.