From the beginning of the article:
Our information about the role of the basileus in Athenian homicide law comes primarily from two sources: Drakon’s law and Antiphon 6 – the first a fragmentary inscription purporting to be a copy of a statute enacted ca. 620, the second a speech for the defense from a trial in 419/8. From such scanty evidence we can hardly hope to compile a thorough, authoritative account of the subject over several centuries, and so it should be understood at the outset that the following is, in my view, the most reasonable account allowed by the evidence in the context of Archaic and Classical political and legal history.