The basis for it, obviously, is to remove any proprietary testing and put the responsibility on third party testing. In the United States, before 2007 and before the Consumer Product Safety Improvement Act was in place, you did not have to have any testing done to the product to import it into the country. It is now mandatory that you have testing done by a third party. The industry in general supported that.
On May 28th, 2009. See this statement in context.