That both parts of the sentence refer to the same person is now generally agreed; it is not so much that a change of subject would be, as the commentators are wont to say, ‘un-Sophoclean’, but simply that it would be awkward and clumsy. But to whom do the lines refer?
D. B. Gregor (C.R. lxiv [1950], 87–8) argues for Clytaemnestra, but despite the apparent force of some of his arguments (e.g. that the clause refers to Clytaemnestra because it is she who picks up Electra, in 616, picks up Clytaemnestra's of 615; but could still be Electra's) I cannot agree. He adds too that the reference to echoes the motif of Electra's speech, but it is just as much the motif of Clytaemnestra's speech, in fact more so. Finally, the first part of the sentence, it is true, could be asserted by the chorus on the strength of some such gesture as the heaving of the bosom, but I cannot see how they could then deduce that Clytaemnestra ‘no longer cares whether justice is on her side’