YLegis is a language and set of associated tools in use by AustLII as part of their DataLex platform.

There is no evidence that YLegis is available as open source software, which is why it is listed as commercial.

According to this paper, YLegis can be used to take an existing piece of legislation and convert it into a “first draft” YScript representation. YScript is the scripting langauge used by the DataLex tool.

According to the same paper, YLegis has another mode that allows for legislation to be drafted in a controlled natural language that can be reliably converted into the corresponding YScript, and used to generate legal expert systems inside the DataLex system.

What differentiates YLegis’s formal mode from other Rules as Code approaches is that it suggests that co-drafting, the idea that legislation should be written in natural languages and software languages at the same time, can be accomplished with a single text which is both natural language and code.