Yes, SHARIA is a Scrabble word!

Letter values in Scrabble US: S 1, H 4, A 1, R 1, I 1, A 1.

Is it a valid word?

SHARIA is a valid word in the official Scrabble dictionary (US) and the UK Scrabble Dictionary, but not in Words with Friends (ENABLE).

the code of law derived from the Koran and from the teachings and example of Mohammed

Also: shariah law, sharia law, islamic law.