Blogs have appeared in a number of cases. A study done in 2006 chronicled 27 references to blogs in court opinions, including one citation by the US Supreme Court. By June 2012, the number had increased to 88, including a second US Supreme Court citation (Mayo Collaborative Servs. v. Prometheus Labs., Inc., 132 S. Ct. 1289 (2012) (citing PatentlyO)). The blogs cited by courts are:
Rank # of Citations Blog
(1) 45 Sentencing Law and Policy (43 fed; 2 state)
(2) 8 Volokh Conspiracy (7 fed; 1 state)
(3) 6 Patently 0 (6 fed)
(4) 4 The Confrontation Blog (1 fed, 3 state)
(5) 3 ProfessorBainbridge (3 state)
(5) 3 Election Law Blog (2 fed; 1 State)
(7) 2 Becker-Posner Blog (1 fed; 1 state)
(7) 2 Credit Slips (1 fed; 1 state)
(7) 2 Ideoblog (2 state)
Another 13 blogs have one court citation each. These include Balkinization (federal); Cases and Materials on Bus. Entities (state); China Law Blog (federal); Evidence Prof Blog (state); Goldman’s Observations (federal); Harvard Forum on Corp. Governance & Financial Regulation; Immigration Law Prof Blog (federal); Instapundit (federal); Legal Theory Blog (state); Legal Insurrection (federal); Lessig Blog (federal); Prawfs Blog (federal); and TheRacetotheBottom (state).
For those who want a look at a complete version of the data, it can be found at Law Faculty Blogs and Disruptive Innovation: the Data.