The Council of Language Access Coordinators Working Group at the National Center for State Courts in the USA offers step-by-step Guidelines for the Development of Legal Glossaries.

The guidelines cover:

• Identifying audience and setting
• Defining the overall scope of the glossary
• Determining the organization and structure of the glossary
• Identifying the best platform for delivery of the glossary
• Selecting and coordinating a team of legal and linguist subject matter experts
• Developing an ongoing maintenance plan.

Appendix A lists legal glossaries issued by various sources, mainly courts, in a considerable number of languages including rarer ones.

There is also a sample project plan for the development of a bilingual legal glossary.

You can find the guidelines here.