Formal Opinion 93-379 of the ABA Standing Committee on Ethics and Professional Responsibility presumably holds even now, a dozen years later. The Opinion concludes that the practice of billing more than one client for the same time is unreasonable and violates Rule 1.5(b) of the Rules of Professional Conduct.
Hooray, and all’s well in heaven. What bedevils me, and may render that statement of ethics nugatory, is the evident difficulty either client would have proving the double-billing transgression. No less than the billing partner might miss it, if the timekeeper records time to clients billed by different partners.
In its guidelines, a law department can mandate compliance with Opinion 93-379, but I recall a phrase from early in our judicial history, to the effect that “Justice Marshall has announced his decision, now let him enforce it!”