In fact, on a day-to-day basis, the European
Commission uses three working
languages — English, French and German.
Draft policy papers and draft legislation
are produced in one or more of
these languages. Only at the final
stages are the texts translated into all
20 official languages.
The European Parliament, which often
needs to produce documents rapidly in
all official languages, has developed a
system of six ‘pivot’ languages. The six
are English, French, German, Italian, Polish
and Spanish. A document presented
in, say, Slovak or Swedish will not be
translated directly into all other 19 languages.
Instead it will be translated into
the pivot languages and then retranslated
from one of them into the others.
This removes the need for translators
able to work directly from Maltese to
Danish or from Estonian to Portuguese,
and hundreds of other combinations as
well. If texts were translated directly
from all official EU languages into all
the others, this would give a total of
380 bilateral combinations.
By word of mouth
EU interpreters use a similar system
when providing full interpretation to
and from all 20 official languages. For
instance, a Finnish speaker’s words will
be interpreted into a limited number of
‘relay’ languages. A Slovenian interpreter,
for example, will plug into one
of these as the source language, removing
the need for people who can interpret
straight out of Finnish into Slovenian.
Using linguistic shortcuts of this kind
makes practical and economic sense –
provided standards are maintained.
Quality control of both interpretation
and written translation is therefore a
major activity.
Interpreters also provide slimmed down
services for informal and working meetings.
In some cases, only the most
widely known EU languages are used.
In others, participants may be able to
speak a larger number of languages but
these are only interpreted into two or
three of the widely used ones. The idea
here is that speakers are free to express
themselves in their own tongue, or a
language they feel comfortable in,
while it is assumed they have enough
passive knowledge of a major EU language
to follow the rest of the proceedings
in that language.
On any one day, the interpretation service
of the European Commission and
the Council of Ministers has to cover
about 50 separate meetings in Brussels
or at other EU locations. An event which
provides full interpretation into and
out of the EU’s 20 official languages
requires a team of 60 interpreters.
With enlargement, more use is being
made of translators and interpreters
able to translate out of as well as into
their mother tongue. Previous standard
EU practice for translators was to work
into their mother tongue only. As
another money-saver, private agencies
are increasingly being used to translate
less essential documents .
Fonto: 
http://europa.eu.int/comm/publications/booklets/move/45/en.pdf
(facilas preni aliajn lingvoversiojn)
venos...
De 
http://europa.eu.int/comm/dgs/translation/navigation/faq/faq_en.htm:
What translation methods does the DG for Translation use?
The external method: The translation is created by a freelance translator and revised by an in-house translator with the target language required.
The two-way method: An in-house translator whose principal language is the source language of a document (the one in which the original was written) and who has an excellent knowledge of the target language translates the document out of his or her principal language.
The relay method: An in-house translator whose principal language is the source language of a document translates it into a relay language, usually English or French, known by another translator who then puts it into the requested target language. This method is used for uncommon language combinations such as from Estonian into Greek.
The three-way method: An in-house translator translates from and into languages of which neither is his or her principal language, as, for example, where an Italian translator puts a text from Arabic into English.