Term variants challenge lexicographers of dictionaries intended to provide help with legal translation into English as a foreign language. General-language lexicography has imported the concepts of description and prescription from linguistics, but these have not acquired terminological status within the field of lexicography. Furthermore, law is a highly culture-bound domain, and several jurisdictions have English as their language but different legal systems. In order to help lexicographers work with term variants within and across jurisdictions, the theory of functional lexicography proposes a third option, called “proscription”, which has Latin roots and refers to making something public. A number of examples show that by using a proscriptive approach in legal translation dictionaries, lexicographers can provide clear and useful guidance to dictionary users by including all legal term variants but explicitly recommending one of the forms. This type of help may guide translators to proper legal usage so that they will use the terms that the readers of the English target texts expect to find.