I've been having trouble with my search for federally banned books. Many searches show books which are banned in local libraries or by the state, but not nationally. The only book I could find that is still banned nationally is "The Political Mafia" by Irwin Schiff. Is there any resources to find out what publications are banned nationally? Also, what is the criteria necessary for the federal government to ban a publication?
The United States has a very liberal attitude when it comes to free speech. Short of materials that are: child pornography, restricted under the International Traffic in Arms Regulations (ITAR), Libelous/Fraudulent, encourage or aid others in breaking the law, or seditious/treasonous/ terroistic/other credible threats there is almost nothing that can't be published. There is another example where supposedly The Golden Book of Chemistry Experiments was banned by the US Government, but I cannot find any evidence or action against the author to support the claim.
The Political Mofia by Schiff was not neccessarily banned, but an injunction from publishing was issued against the authors in US v. Schiff, 379 F. 3d 621 - Court of Appeals, 9th Circuit 2004 per 26 U.S.C. 7408 on grounds that the books was fraudulent.
Essentially it is the Federal courts that can ban a book from commerce with cause. Schools, libraries and other institutions may ban it from their collections, but not from public commerce. Wikipedia has a list of Books banned by governments that you may want to look at to find examples.