This is the actual policy language for the new "Kidney Allocation System" for the US, effective December 4th, 2014. This is regarding kidneys from deceased donors only. There are a lot of details, but it's supposed to be simpler, more just, more equitable, more fair, and a more effective system than the existing ones.
http://optn.transplant.hrsa.gov/ContentDocuments/Policy8_Update_KAS_12-2014.pdf