I believe the ability to file such a suit came about with a new law created by Congress which enabled the Lockerbee victims to sue Libya.
Emotions don't make good law, and this one will surely cut two ways. These victims may obtain what they consider justice, but when American courts do not uphold the sovereignty of other nations, what price will we pay?
Well, the UN and ICC already apparentely feel that they over-ride the sovereignty of the United States already. . . .