I think most US residents on HN live in a state where blacklisting is illegal. Washington state and New York have labour laws against blacklisting while California has a law against employers preventing previous employees from finding work. I wouldn't be surprised if most states had laws like New York, Washington or California.

California Labor Code 1050-1053 may apply to blacklisting: http://www.leginfo.ca.gov/cgi-bin/displaycode?section=lab&gr...

Revised Code of Washington, 49.44.010 explicitly lists blacklisting as a prohibited labor practice. http://apps.leg.wa.gov/rcw/default.aspx?cite=49.44.010

NY Labor Law Section 704 lists blacklisting as an unfair labor practice. http://public.leginfo.state.ny.us/LAWSSEAF.cgi?QUERYTYPE=LAW...