IANAL (I Am Not A Lawyer) is a programming language. Programs in this language are presented in the form of a legal contract, and they run with the aid of a human interpreter (preferably a lawyer) or a team of human interpreters working in parallel. IANAL code is very powerful and very flexible, which may lead to disagreements over its semantics. Ultimately, the formal semantics of IANAL are determined by the courts.
IANAL is Turing-complete and has built-in Machine Learning, Natural Language Processing, and Computer Vision features, such as the famous "I know it when I see it" rule.
IANAL is in widespread use today, and indeed most pieces of software contain a small amount of IANAL code. Many humans across the world go through an intensive multi-year study program to become competent programmers and interpreters of IANAL, and the IANAL programming career is strong -- although certified IANAL programmers tend to write in a more formal variant of the language called IAAL (I Am A Lawyer).
The cryptocurrency "Fiat Money" also has widespread adoption and was written in IANAL, though this was invented prior to the discovery of blockchain technology. The double-spending problem is solved either by passing around physical tokens ("Cash") or employing a central authority ("Bank"). Smart contracts written in IANAL are often backed by this cryptocurrency.