I' d like to attend a free online PHD

There is no free program that really has any value and there would be none that are accredited.

In cases like this you get exactly what you pay for, nothing..

While you cannot get a free online Ph.D. in political science, history or law, there are many solid online resources (with lectures, videos, etc.) to help you study these topics without attaining a degree.

Here are a few:

Political Philosophy with Steven B. Smith at Yale
Introduction to Political Philosophy — Open Yale Courses

Criminal Law with Tamara Lave at UC Berkeley (iTunes audio)
Legal Studies 109, 001|Fall 2009|UC Berkeley - Download free content from UC Berkeley on iTunes

World War II with Charles Maier at Harvard (video lectures)
Free World War 2 Course | Open Harvard Course

Hope this helps and good luck with your studies!