Is this against the law, or just the way things are done now? My gut instinct would be there's more examination that goes into a drone strike but after the Snowden revelations I don't know what to believe.
Another issue could be about the quality of the briefing: if the phone call was all she got, it might mean that she wasn’t briefed enough to review the evidence and make an informed decision.
However, I think that this just goes to the line: she was reckless with confidential information — which, at this level, is against the law.