Government and pro-government forces have continued to conduct widespread attacks on the civilian population, committing murder, torture, rape and enforced disappearance as crimes against humanity. They have laid siege to neighbourhoods and subjected them to indiscriminate shelling. Government forces have committed gross violations of human rights and the war crimes of torture, hostage-taking, murder, execution without due process, rape, attacking protected objects and pillage.
Anti-government armed groups have committed war crimes, including murder, execution without due process, torture, hostage-taking and attacking protected objects. They have besieged and indiscriminately shelled civilian neighbourhoods.
Anti-government and Kurdish armed groups have recruited and used child soldiers in hostilities.
The perpetrators of these violations and crimes, on all sides, act in defiance of international law.
This is nearly never the case! If Assad systematically conducts atrocities to say thousands of civilians, and the rebels retaliate by killing only 1, the statement that "both sides committed atrocities" could still hold. If the reverse is to occur then the statement still holds.
What should be done is see which party is victimized most, and it is always the civilians! It is those that should be supported, their oppressors kicked (on any side they may come), empowered into a throne democratically, and then the ones who did atrocities to be indicted to a proper legal court. Never fall for the statement "well the two sides have blood on their hands" for it always undermines the amount, the methods, the details, that were used.