Whether in corporate transactions, litigation or business disputes, there may be situations in which multiple separate entities seek to enter into a formal relationship to protect their shared interests, even when represented by separate attorneys. If these entities are co-defendants to an ongoing litigation, they may wish to document the joint defense they share and their intent not to waive attorney-client privilege by sharing strategies and resources. For entities who are not involved in litigation, but who share an interest in a legal issue (such as negotiating a transaction or an ongoing lobbying interest), they may desire to document their common interest.