Judges’ scholarly writing as a source of common law

The sunset of Lord Sumption’s judicial career, and the new dawn of his life in the academe, is a reminder of the relationship between judicial writing and legal scholarship. Although Lord Neuberger has suggested that judges and professors are ‘ships passing in the night’, who only occasionally speak to one another, many judges engage in the kind of academic or ‘scholarly’ extrajudicial writing more familiar to law professors. Some have had past lives within law faculties; others may write as a public service; others, because it is their passion. What is the status of that commentary? May it be treated as a source of law?