The following language, or something similar, could be used as a stand-alone document or incorporated into a broader lease agreement:
ABC Law Firm and XYZ Law Firm have entered into an agreement under which XYZ Law Firm is sub-leasing office space from ABC Law Firm at __________Street, Suite _____, in City, State. The relationship between the parties to this agreement is solely that of landlord-tenant. The firms are not associated in any other way and do not intend to create any association or partnership of any sort by virtue of this arrangement or this agreement.
Each firm acknowledges and agrees that it, its members and staff are ethically obligated to maintain its clients confidences. To safeguard the confidentiality of ABC Law Firms work product and client communications, XYZ Law Firm agrees to avoid any contact with ABC Law Firms computer system, case files, or written or oral inter-office communications. ABC Law Firm likewise agrees to avoid contact with XYZ Law Firms computer system, case files or inter-office communications. Particular care will be taken by the employees of each firm to avoid accidental disclosures of confidential information in shared areas such as the library, the office services areas, restrooms, hallways, and elevators.
ABC Law Firm and XYZ Law Firm also agree to notify each other immediately should either firm come to represent any party in litigation in which the other firm also represents a party, or in the event of any conflict of interest between clients of the two firms. In the event such a situation arises, ABC Law Firm and XYZ Law Firm agree to prevent the intentional or accidental disclosure of client confidences or work product by taking mutually agreed upon measures, such as: limiting access to each firms library and records storage areas to members of the respective firm; notifying all employees of both firms of the special need to prevent such disclosures in the matter; notifying and seeking consent of clients as necessary; and any other measures deemed appropriate.
ABC Law Firm and XYZ Law Firm agree to take all necessary steps to ensure that their personnel fully abide by this agreement and specifically agree to circulate a copy of this agreement to all of their respective employees.
Dated: __________________ XYZ Law Firm
Dated:___________________ ABC Law Firm