What exactly is Natural Law and why are Conservatives paranoid about people knocking it down.

I don't exactly get into philosophical debates. My brother however flipped a fully loaded couch table at mom calling her a traitor to her face for saying that he has a right to his opinion about whatever Natural Law is. Which I basically came up with He's into Declarationism and only 1 Supreme Court member might be one (Clarence)

What my brother says: Natural Law has been around since the first Humans were created.

What I've read. Judges couldn't implement it and stuck with Common Law. Common Law governs the USA. His answer.... the phrase No One Is Above The Law is straight Natural Law. I guess this is why he's leaving Facebook. They are anti American because they are against Natural Law.

Like I'm not a big one on Arisotle (sp) but thats old hat. Question I have is why is this suddenly an issue with ultra Conservatives (mind you my brother was big on Howard Dean but then swung hard right not long after) . I still consider philosphy a form of an opinion and fact at the same time I'm just hoping for some insight on where this outright hate of those who don't hold to Natural Law comes from. I could ask my cousin in law about it (he is now officially a lawyer in MN. But I don't think thats the sort of Law one just looks up.

The reason he originally said he is leaving Facebook for something called MEWE or WEME is because FB is banning Gun companies from having discussions. Oddly in the Y's my Y is theology . But again thats a debate that only those who know what they are talking about should be having.