• I feel you have titled your query wrongly. You are not looking for ‘US Visa Policy’, instead you are attempting to form a policy to retain employees who have been granted visa and in case such employee leaves you, what will be the penal action. It is clear that, your company is trying to mitigate the risk of loosing the employees who have got visa and who are likely to leave you for greener pastures.
• One part of the policy is already decided by you that you want employee to continue with you minimum for 18 months from the last day of overseas travel.
• Next part of the policy will include the penalty employee will have to bear in case he/she decides to leave before completion of 18 months. While deciding the penalty you will have to think of right figure, so that you can really discourage employee from leaving and you are also able to recover amount spent on employee on training, travel abroad and stay abroad.
• Next part of policy is to how to enforce the policy. I feel you have no other option but to have a legal bond executed from employee at the time of sending them abroad, rather employee will be sent abroad only in case he/she executes the bond.
• Take due care to properly frame and draft the bond taking proper and practical legal advise so that bond can be invoked in case of need and will stand the scrutiny of law of land and courts.
• To further safeguard your interests, you can ask for further sureties and guarantors from employees’ side and get surety/guarantee agreements executed from them.