While most jurisdictions do not require formal written agreement to recognize a common defence privilege, the best method is to document the extent, duration, limits and parties to the common privilege of the defence. If left uncorrected, these differences can jeopardize all parties to the common defence agreement. An important provision of any common defence agreement is therefore to deal precisely with what happens when a party decides to denounce or abandon it. Common defence and common interest agreements can be effective instruments to promote client interests and reduce costs. The key is to do them properly so that they do not become the basis of litigation themselves. In litigation, co-accused often have a common interest in defeating the complainant`s claims. Especially in situations where co-accused do not attempt to blame the blame, the courts have recognized that the accused can defend themselves together and share trust and secrets (as well as expenses). In this context, communications between the defendants would not be protected in subsequent disputes between them, but communications would be protected from discovery by the applicants. From a strictly legal point of view, the common privilege of defence is a bad name, for it is not in fact a positive privilege; Rather, it is an exception to the exemption granted to the exemption. In general, the disclosure of privileged and confidential information to third parties constitutes a waiver of privilege.
However, those who are protected by a common defence agreement can avoid relinquishing and retaining the privilege, regardless of the disclosure of confidential information to third parties. To obtain the privilege of communicating with others, a party must generally show three things: that the communication ended in a common defence, that the communications were made to support the objectives of that common defence, and that the privilege was not nullified elsewhere (i.e. that the common defenders do not share communication beyond their small group). Nevertheless, there is sufficient commonality for lawyers to maximize the chances of each court recognizing and effectively recognizing the privileges and immunities of common interest claimed. This is usually done through a formal written agreement. There will be cases where a co-accused will attempt to monopolize the direction of the legal strategy within the framework of a JDA to use himself. Collaborative defence counsel must be tired in these situations, as a court may find that there is no JDA in such circumstances. The terms, scope and limitations of the common privilege of the defence or the privilege of the common interest may vary considerably depending on jurisdiction. State and federal jurisdictions are different from whether they recognize a common law of defence or a privilege of common interest and to what extent such a privilege applies. Common defence relationships may exist between civil or co-accused parties and in a civil or criminal context.
A common defence may even extend to non-parties, such as defendants` insurers. When a party to a common defense agreement decides to cooperate with the government, the potential for disclosure of confidential information also threatens other sixth amendment rights. (Quotes are omitted). Federal courts have an independent interest in streamlining criminal proceedings within the ethical standards of the profession and for judicial proceedings to appear fair to all who observe them. Courts also have an independent interest in protecting a fair trial from trial tactics that can be used to create appeal issues. Given the high potential for absurdity, courts have every right to seek common defence agreements before making problems.  Weissman invoked the common privilege of the defence to ensure that his own confessions were not used against him.