Some recent NACE papers addressing the two -850mVcse criteria in NACE SP0168-2007 have contained errors in describing the background of the criteria which perpetuates the confusion that is endemic in the cathodic protection industry. This paper traces the empirical roots which affected the development of these -850mVcse criteria. The historical record covers the work of R.J.Khun Shwerdtfeger and McDorman at the National Bureau of Standards AGA laboratory and field studies conducted by Barlo and Berry and a number of European investigators. Review of this body of work clarifies the interpretation of the of the -850mVcse criterion which should result in resolving the mistaken impression that there are two distinct criteria. Fundamental analysis of these criteria in conjunction with rigorous interpretation of the pipe-to-soil potential measurement supports the conclusion that the two criteria are essentially equivalent. Convincing certain sectors of the pipeline industry of this conclusion remains a considerable challenge.