Found close to Eretria in Euboea, this important inscription of the mid-4th c. BC has long remained unpublished. It is a large stele with the top and left side cut away, on which 35 lines are engraved stoichedon (with 51 letters per line after restoration). Based on the find spot, language and content, it may be related to fragment IG XII 9, 190, in spite of the fact that this small piece--lost long ago--was not presented as a stoichedon text by its only transcriber. Putting the two together enables a surer restoration than hitherto of the fragment in question (A): it is the beginning of the law, with the statement of the rewards to be expected by a tyrannicide, adjusted according to his political and social status. The text of the new fragment (B) itself comprises two sections, distinguished by a significant asyndeton. The first section (l. 1-17) comprises a series of clauses, the object of which was to protect the democratic constitution against any attempt to install a tyrannical regime by using the subterfuge of a subversive motion: the contravener would find himself not only deprived of his civic rights (discussion about the notion of atimia at this time) and his goods (confiscation by the state--with a tithe for Artemis Amarysia, whose preeminence in the Eretrian pantheon is thus confirmed), but proscribed in perpetuity (interdiction against the interment of his remains in the Eretriade or Eretrias ge; immunity and even a reward granted to his murderer). This first section ends with a solemn curse aimed at discouraging any attempt against the provisions of the law itself (interesting role of the priests and priestesses--with a rare, if not even new--word, hieris for hiereia--at the time of the Dionysia and Artemisia); between the terms of this curse and the wording of the great 'international' oaths (attested precisely from the 4th century on) there is more than one point in common to consider.