Apparently she was driving drunk, also.
I think the law is that you are guilty of vehicular manslaughter purely by reason of being involved in an deadly accident while intoxicated. What the other person was doing is irrelevant.
Also, as an aside, the issue of red and green lights isn't as clear as people think. A green only means that you can proceed through the intersection if the intersection is clear and it is safe to do so. If someone is coming through, regardless of the colour of the lights, you're not allowed to enter the intersection. When it comes to right of way in an intersection, possession is
ten tenths of the law.
ETA: Reports all seem to say that Leyritz' car hit Fredia Veitch's, which suggests that she was in the intersection first. If so, that will evaporate Leyritz' (probably irrelevant) defense about who had right of way. However, Veitch's BAL (.18) was higher than Leyritz' (.14), which will likely have an impact in the wrongful death suit filed by Veitch's family.
Also, just because Leyritz drunkenly killed someone who may have, one day, drunkenly killed someone else does not make him any less of a douche. It's not like he knew she was as drunk as him when he plowed into her car.