I've been hunting around for this thing forever and finally saw it mentioned in a Clive Crook commentary on the health care law. One of the arguments used in favor of requiring the uninsured to get insured is that the law requires that emergency health care be provided to anyone that requires it. Here's the law that establishes that: Emergency Medical Treatment and Active Labor Act.
From Wikipedia: It requires hospitals and ambulance services to provide care to anyone needing emergency healthcare treatment regardless of citizenship, legal status or ability to pay. There are no reimbursement provisions. As a result of the act, patients needing emergency treatment can be discharged only under their own informed consent or when their condition requires transfer to a hospital better equipped to administer the treatment.
Those who are not insured, impose costs on those that are. This is the argument used to justify the law under the commerce clause.
