He's probably not someone you've ever heard of, because when textbooks start listing great philosophers and thinkers he doesn't often make the cut.

But that's unfair and here's why: he made the Magna Carta relevant hundreds of years after it had been written. In fact, he's why you're learning about it right now. He took an ancient, medieval text and said, "Listen up, people, this old thing is chock full of good ideas that we need to put into our government right away."

Lawyers win cases if they can cite precedents and Sir Coke was the first to drag out the ultimate precedent (the Magna Carta) and slap everyone around with it. (Source)