Isaeus was, like Lysias, a metic - in his case, from Chalcis.
Very little is known of his life. He will have been active during
the first half of the 4th century. His speciality, as we
can see from the eleven speeches of his that survive, was
inheritance cases. This does not necessarily mean that he did not
work in other areas of forensic oratory as well. As you might
expect, his speeches are our basic source for the law of
inheritance and kinship relations at that time.