The government banned the sale of organs, effective March 2008.[39] Since the ban took effect, the number of transplants has decreased from 1,046 in 2007 to 511 in 2010.[40] Professor Roger Lee Mendoza has suggested that declining numbers of transplant tourists and documented organ sales may serve to strengthen organ black markets. Often, he says, banning organ sales fosters compensation-based contractual systems between underground donors, brokers, and buyers.[41]