[1] The Innocent Third Party: Victims of Paternity Fraud (110 kB PDF file)
BY RONALD K. HENRY; Family Law Quarterly, Volume 40, Number 1, Spring 2006

This is the best overview yet written by anyone I saw on the scope and nature of paternity fraud and related issues. — WHS
From the article:

The bottom line in the drive to find some man, any man, to drive up the paternity establishment rate is that “fairness was not a high concern.”….

In Los Angeles County, eighty percent of paternity establishments are entered by default judgment, whereas for the State of California as a whole, the number is sixty-eight percent.  California is not alone. The United States Department of Health and Human Services Office of Inspector General (HHS/IG report) reported that “seven states’ child support agencies report half or more of paternities established in their states occur through defaults.” The inspector general further reported that “[t]wentyfour percent of local offices in focus states report half or more of paternities in their caseloads are established by default.”
([2] Full Story)