PRECAUTIONARY PRINCIPLE USED IN DRUG APPROVALS. “When a drug company wants to market a new drug, we ask them to provide reasonable evidence of no harm and we ask them to show that their new product will do some good (they must show “efficacy”). The assumption is that a new drug will be harmful or useless (or both) and it’s up to the company to prove otherwise.”
http://www.multinationalmonitor.org/mm2009/032009/interview-montague.html