The party invoking the privilege bears the burden of proof of the existence of the privilege. Andrews J. stated that the applicants had not fulfilled their burden of proof of the finding of a common legal interest for two reasons: (1) The documents were provided before an agreement was reached between Hamilton Capital and the applicant and (2) the communications were exchanged before a dispute was filed. Id. at *9. The essential feature missing from the applicant`s argument was therefore that they were not in a capacity to prove that the applicant and Hamilton Capital were allies on a common legal ground at the time of communication. Based on the above, prudent counsel may conclude that a JDA is simply never worth the effort. Although a written agreement is not required, it can be difficult to prove that an oral agreement was reached and that it was binding. In addition, the agreement of common interest should clearly define the common interest of the law. The defendants learned this the hard way at United States v. Krug.
 A written JDA was concluded in Krug by the co-defendants and their lawyers. In addition, disclosures must have been made for the purpose of “securing, promoting or providing legal representation.” See Dans re Regents of the Univ. of Cal, 101 F.3d at 1389 (cited in re grand jury Subpoena Duces Tecum, 406 F. Supp. 381, 386 (S.D.N.Y. 1975)); See also In re Bevill, Bresler & Schulman Asset Mgmt. Corp., 805 F.2d 120, 126 (3d Cir. 1986). .