Judgement is a British spelling of the word usually spelled in North America as "judgment," without the "e." If you're going to sit in judgement of proper spelling, make sure you're sitting on the eastern side of the Atlantic.
The spellings judgement and judgment have both been available since the sixteenth century. Americans have opted for the "e"-less spelling, while judgement has lingered in the U.K. But even there, judgment has now become the conventional spelling in legal usage. Use your judg(e)ment when deciding how to spell this word, and leave out the "e" for an American audience.