28 C.F.R. § 543.14

(a) An act by an attorney which violates Bureau regulations or institution guidelines and which threatens the security, good order, or discipline of the institution is grounds for limitation or denial by the Warden of the attorney's privileged visitation and correspondence rights. Acts by an attorney which may warrant such limitation or denial include, for example the following:

(1) A false statement as to the attorney's identity or qualifications;

(2) A plan, attempt, or act to introduce contraband into the institution;

(3) A conspiracy to commit, an attempt to commit, or the actual commission of an act of violence within an institution; and

(4) Encouraging an inmate to violate the law, Bureau of Prisons rules, or local implementing guidelines.

(b) Unless the breach of regulations is extreme or repeated, limitation rather than a denial of visitation or correspondence rights is proper, especially where the inmate is represented by the attorney and is confronted with a court deadline. For example, the Warden may subject an attorney to a search of his person and belongings or may permit the attorney only non-privileged correspondence. The Warden shall also consider referral of the matter to the state agency regulating the attorney's professional conduct.

(c) An act by an inmate in violation of Bureau regulations or institution guidelines warrants a limitation by the Warden of the inmate's correspondence or visiting rights with attorneys only if necessary to protect institution security, good order, or discipline. The Warden may not deny correspondence or visiting rights with attorneys generally.

(d) The attorney may appeal any limitation or denial by the Warden of attorney visits or correspondence rights to the Regional Director. The inmate affected may appeal through the Administrative Remedy Procedures.