It's about 20 years old. It started, really, with Evan Stark, and grew out of the power and control wheel from the Duluth model 20 years before that. However, the details have filled in more with time, with more examples coming from real life and with talking to more victims.
One of the things I have sent to the committee is a checklist that we're using now locally. It is really detailed about questions to ask to identify coercive control.