On some of the billboard posters, however, this is written as 'Judgement is Coming'.
As a copy editor, it is best not to be pedantic, and few people appreciate this kind of quibbling. The laws of spelling are descriptive, rather than prescriptive. This is not to say that anything goes. Laws exist to formalize ordinary usage rather than to tickle the whims of elitist nit-pickers. Meanings change, language is in flux, and internal consistency is more important than the mindless application of a dusty orthodoxy. For the sake of elegance and comprehension, a balance needs to be struck.
But then it occurred to me that the inconsistency in the Dredd 3D publicity is probably deliberate. Of course! The difference in spellings undoubtedly signals an important and subtle narrative point. In the course of the film's story, Dredd himself will be forced to wrestle with an inconsistency between the judgment it is his duty to dish out as a law enforcer and the personal judgement his conscience demands. Like a copy editor, he must learn to reconcile the two. How clever.
Judge Dredd and I have a lot in common.