Tjyylli

This rather old article argues about EU countries actual influence within the EU:

Germany is over-represented in the European Parliament, giving it a
correspondingly high potential to influence EU policies, while other
countries are at disadvantage, according to a recent report by a
Romanian think-tank. EURACTIV Romania reports.

Qvorum, a non-partisan think-tank which aims to stimulate citizens’
and social partners’ involvement in the policymaking process,
discovered that a number of countries have won privileged
representation in the assembly’s governing bodies, while other nations
are clearly under-represented.

Ten years have passed and I expect things to have changed. I am wondering if there is a more recent influence related article.

However, I am mainly interested in the causes of this difference in "influence". I expect that some objective facts such as population or GDP to be an important factor in influencing the number of representatives within an EU structure.

Question: How is number of representatives within EU structures computed?

For the EC and the ECJ, the rule is straightforward: it's one appointment per member state.

For the EP, the general idea is to give similar representation to each country based on their population, with two twists:

• Early on, smaller countries got a few bonus seats so larger countries (Germany, France, Italy at the time) couldn't simply band together and push them around. These bonus seats stuck around over time. (This is similar in spirit to what the Bundesrat does and it is called degressive proportionality.)




• For political reasons, countries of similar size have traditionally been given the same number of seats. For instance France, Italy, and the UK (until 2014, when France got a bonus seat); or Spain and Poland; and so forth.

Note: you can see Article 15 of the TEU for the European Council, Article 19 for the Court of Justice, and different sections of the TFEU for the European Central Bank and the Court of Auditors. It's fairly straightforward since it mostly requires a representative by member plus a president (or other similar positions). As so I'll focus on this answer on the EU parliament which has more complex (and "flexible") rules.

The allocation (apportionment) of seats in the EU parliament is decided by treaty following the rules exposed in Article 14 of the Treaty on European Union. Furthermore the actual composition is decided by the European Council.

Article 14

1. The European Parliament shall, jointly with the Council, exercise legislative and budgetary functions. It shall exercise functions of
   political control and consultation as laid down in the Treaties. It
   shall elect the President of the Commission.




2. The European Parliament shall be composed of representatives of the Union's citizens. They shall not exceed seven hundred and fifty in
   number, plus the President. Representation of citizens shall be
   degressively proportional, with a minimum threshold of six members per
   Member State. No Member State shall be allocated more than ninety-six
   seats. The European Council shall adopt by unanimity, on the
   initiative of the European Parliament and with its consent, a decision
   establishing the composition of the European Parliament, respecting
   the principles referred to in the first subparagraph.




3. The members of the European Parliament shall be elected for a term of five years by direct universal suffrage in a free and secret
   ballot.




4. The European Parliament shall elect its President and its officers from among its members.

To give a more practical example. Last year the European Council decided on the new rules of the parliament composition after the UK left the EU. The rules they choose are these:

Article 1

In the application of Article 14(2) TEU, the following principles
shall be respected:

– the allocation of seats in the European Parliament is to fully
utilise the minimum and maximum thresholds per Member State set by the
TEU in order to reflect as closely as possible the sizes of the
respective populations of the Member States,

– degressive proportionality is to be defined as follows: the ratio
between the population and the number of seats of each Member State
before rounding to whole numbers is to vary in relation to their
respective populations in such a way that each Member of the European
Parliament from a more populous Member State represents more citizens
than each Member of the European Parliament from a less populous
Member State and, conversely, that the larger the population of a
Member State, the greater its entitlement to a large number of seats
in the European Parliament,

– the allocation of seats in the European Parliament is to reflect
demographic developments in the Member States

Just as a curiosity this would be the new allocation of seats in the EU parliament.

NOTE: this will likely not be followed considering the latest developments on Brexit. It's in this answer for illustration purposes only.