Michelle's Law - Amends the Employee Retirement Income Security Act of 1974 (ERISA) and the Internal Revenue Code of 1986 to prohibit a group health plan or health insurance coverage offered in connection with such a plan from terminating the coverage of a dependent child due to a medically necessary leave of absence from a postsecondary educational institution that causes the child to lose full-time status before the date that is the earlier of: (1) one year after the first day of the leave of absence; or (2) the date on which such coverage would otherwise terminate under the terms of the plan. Requires documentation and a certification by a physician.