The ICRC has stated that the violence in Syria constitutes an non-international armed conflict. This is significant because it means the organization tasked with guarding and promoting the Geneva Conventions is declaring that at least portions of the Geneva Conventions (especially Common Article 3) applies to the conflict and unlawful attacks on non-combatants could be prosecuted as war crimes.
At Lawfare Blog, University of Texas’ Robert Chesney has a terrific round-up of legal questions this raises, including the “legal geography of war,” whether Assad will draw on precedent set by US targeted killings to argue that some noncombatants are legitimate targets, whether the war is already internationalized, and how far the ICRC’s view on the matter is decisive.
One other thing that should be noted: Reuters’ story on this declaration makes it sound as if heretofore atrocities against civilians were beyond judicial scrutiny, though as Chesney notes the article does point out that human rights law did and continues to apply. But in fact most of the previous violence in Syria would also be judiciable through the concept of “crimes against humanity” under the Rome Statute of the ICC. Of course, since Syria has signed but not ratified the Rome Statute, the court would only have jurisdiction if Assad or a ranking official traveled to the territory of a state party and were extradited the court, or if the Security Council were to act.  Since this appears unlikely, any international war crimes court would need to be constituted ad hoc, most likely by a regional organization. Still, governments could also try Assad or his officials under the principle of universal jurisdiction for some crimes, notably torture.
Like Chesney, I found the passage on the applicability of IHRL in Syria now that it is classified as a non-international armed conflict interesting. By saying that IHRL continues to apply in areas outside of hostilities, the ICRC seems to suggest it no longer applies in areas within the hostilities. But that is not true- there are many areas in which IHRL and IHL work in tandem. For instance, IHRL requires that violations to the right to life not be arbitrary. IHL then determines what is considered arbitrary- adherence to the principle of distinction is one way to comply with this IHRL obligation. Furthermore, IHRL still applies to activities that may not be considered part of the armed conflict but that occur in zones of hostilities (criminal actions).
I wondered about this to – not because I disagree, but because it seems to go against what the ICRC has been recently arguing…. plus, as you mention, civilians are *normally* better off with HRL as opposed to IHL, *if* the domestic HRL is a strong regime. IHRL is typically less  strong than most domestic HRL, but possibly not in the case of Syria…. so yes… confusing.
I meant to say non-armed conflict related criminal actions
Small nitpick: Assad traveling to the territory of a State Party would not affect the ICC’s ability to exercise jurisdiction over crimes in Syria. The only way for the situation to come before the court is through a Security Council referral. (It would only be subsequent to such a referral that Assad would have to watch where he traveled.)Â