According to this site, which rates the level of education needed for reading different blogs, the Legal History Blog is at "Genius" level. According to Concurring Opinions, some other Genius blogs are: Legal Theory Blog, Balkinization, Becker-Posner and TaxProf.
Coming in at the "Junior High" level were: Volokh Conspiracy, Above the Law, Althouse, Instapundit, CNN, and New York Times.
I checked out Cliopatria, and it weighed in at College (Postgrad), same as Brian Leiter. Readers of AHA Today, the American Historical Association blog, are Geniuses. But we knew that about historians.