I suspect that you can't take any action against your employer for this. As part of your initial employment, you more than likley signed something permitting this or in some other way agreed to give your emloyer permission to check into your background as it sees fit, including taking any acton that is necessary for doing so such as allowing your employer to disclose your SSN to a third party as necessary. And since you did not enter it onto the form yourself, your employer's disclosing it was necessary. You can check your company handbook or other policy statement, employment contract, etc. regarding this. The fact is that an employee's rights are somewhat limited in employment situations; courts have permitted for a lower expectation of privacy. So unless, you have something in the nature of an employment/union agreement or the like, your employer was most probably within its legal authority to take the action that it did.For further information regarding your specific state's law, contact your state's department of labor or an employment attorney in your area.