If you have been in the translation business as long as I have, you have probably amassed your fair share of dictionaries and glossaries. As legal translations are my specialty, I have taken great pains to buy as many Spanish-English legal dictionaries/glossaries as possible.
To get the most out of your money and time spent researching, it is important to have resources with concise translations for each term that suit your translation style. There are many works on the market that have terms that are more explanatory than they are translations.
I have read mixed reports about the Wiley's English-Spanish Spanish-English dictionaries. Some translators are not keen about the "word list" aspect about them. Although I wouldn't use this dictionary as my primary source for legal translations, I have found terms that I hadn't come across in my other legal resources (It has a total of 40,00 of them).
If you have many Spanish<>English legal dictionaries/glossaries, perhaps you don't need this one, but if you only have a few, I recommend it.