Almost all professors in law schools have a law degree. Traditionally, this was the only academic credential necessary for teaching in law schools, but in the last decade or so, a growing percentage of law professors have PhDs in addition to or instead of JDs—about 25% of professors at the most selective law schools. (Some may have LLMs – a master’s degree in law – or, more rarely, JSDs – a doctorate of law).
For teaching law in four-year undergraduate liberal arts institutions, however, a JD is generally insufficient. Almost all such professors have PhDs, most often in the social sciences. Among professors in law-related pre-professional programs (such as paralegal certification programs) or in community colleges, JDs (without a PhD) are more common.