In America, “judgment” remains the dominant spelling, with a factor of more than 10 to 1. The gap was even greater before about 2010:
(The graph shows the ratio of uses of “Judgment” divided by uses of “Judgment”, which is less than 10%.) The gap is also wide in American legal sources; A quick Westlaw search last week found 2,800 cases mentioning “judgment” and 72 mentioning “judgment”.
Strangely enough, “judgment” has become a fairly common variant lately in England, and it has been used at least half as often as “judgment” for several decades (so that a third of the uses of both have the additional “e”). ).
I suspect that both are standard in normal British English (I can’t speak British law), just as “gray” and “gray” are both standard equivalents. But that’s only in the UK; In America, “judgment,” as oddly as it may be spelled, is the predominant form and the use of the spelling “judgment” is particularly likely to be viewed as a mistake.