I looked in the Corpus of Contemporary American English (COCA), and the British National Corpus (BNC), and found this data:
COCA:
1 JUDGMENT 15116
2 JUDGEMENT 584
Ratio in American usage: 25 to 1 in favor of judgment
BNC:
1 JUDGMENT 3220
2 JUDGEMENT 2441
Ratio in British usage: 1.3 to 1 in favor of judgment
So, it does appear that while judgment is more common in both British and American English, judgement enjoys a substantial percentage of usage in British English, but much less in American English.
Addendum: per ShreevatsaR’s suggestion, I searched the BNC again, this time excluding all the spoken sections (“S_*”) as well as the two written legal sections: “W_nonac_law”, “W_ac_law_edu”, and got these results
1 JUDGEMENT 2053
2 JUDGMENT 1317
We do now find the numbers inverted: the ratio of judgment to judgement is just 0.64. Although many of the examples remaining of judgment are in fact in a legal context anyway, we do find, though, that the spelling judgment nevertheless enjoys considerable usage in non-legal contexts. Here are a few examples:
- “Efficiency at work is decreased and judgment impaired, with possible serious results.”
- “There I had him as a charming, affectionate colleague of mature judgment.”
- “It is not pleasant for a human being to pass judgment on another and say that he is evil through and through without any redeeming features”
- “Judgment of humorous writing is even more subjective than with any other kind.”
Best Answer
In American English and British English swop is a variant spelling of swap. (See the also swop note at the top of the page.)
The copy of the NOAD I had on my Mac Mini explicitly said swop is a variant spelling of swap, and also reported swop as chiefly British.