Multilingual websites are the perfect place to find terminology used in context. Particularly useful in my field (law) are the websites of the European Union, the World Intellectual Property Organization and the European Patent Office. Fast access to multilingual websites can also be obtained via Linguee.
Check the source
Again, do check the source before accepting what you find on multilingual websites. There are both fruits and pitfalls out there. Not every website available in more than one language has been translated well by a professional translator. If your term is so remote that you do have to rely on less authoritative sources, do cross-check your potential term in a monolingual dictionary to make sure that the term is indeed a suitable translation.
Practical hints and tips
After I started writing this post I remembered where it was that I first learnt about effectively searching multilingual websites. It was back in around 2003 when I was at the very beginning of my career working as an in-house legal translator at a large commercial law firm and it was at a course entitled Research Techniques for Translators in Zurich which was the first course I was ever sent on. I just googled the course and was happy to see that Tanya Harvey Ciampi is still running the course, albeit in a slightly different format. She has a lot of useful tools on her website which you can access here: http://www.multilingual.ch/search_interfaces.htm and I also found this short YouTube video which might be of interest to some of you: http://www.youtube.com/TranslatorTips
Create your own TM
The European Commission’s Directorate-General for Translation first made the Translation Memory of its Acquis communautaire publically accessible in 2007. It was most recently updated in 2012. This is an excellent resource, not only for legal translators but also for translators in other fields. It claims to be the biggest parallel corpus taking account of the number of translation units and the number of languages it covers. The instructions for downloading the relevant language files for your working languages and how to create the files to load into your TM can be found here http://ipsc.jrc.ec.europa.eu/index.php?id=197. It is not as complicated as it may look at first glance and is a terminology goldmine. If you are working with Trados Studio, don’t forget to use your newly created TM to produce an Autosuggest dictionary for yourself too.