Who has the right to vote in members of the European Parliament?

According to Article 14 of the Treaty on European Union, members of the European Parliament are to be elected for a five-year term by "direct universal suffrage in a free and secret ballot." Every EU citizen has the right to engage politically, by voting (active) or by being nominated for an election (passive), once he or she has reached the statutory voting age.

This minimum age is determined by the individual member states: in Germany, for example, a person must be 18 to cast a ballot. In neighboring Austria, however, teenagers are able to vote once they reach 16, but must be 18 to be run for a seat. In France, the active voting age is 18, while the passive is 23.

EU citizens who live in another EU member state but have retained citizenship in their home country are able to choose in which country to cast their ballot. This also applies to people with dual EU citizenship.

How does the EU allocate parliamentary mandates?

Members of parliament (MEPs) are selected by proportional representation, the exact form of which is determined by the member states.

Each country state has a fixed number of seats in parliament, distributed based on the principle of degressive proportionality. This means that larger member states send a higher number of delegates to Brussels compared with smaller states. However, smaller countries are ensured more seats per inhabitant compared with larger countries. This principle, however, is not without its problems.

What is the purpose of degressive proportionality, and what's the problem with it?

Degressive proportionality is meant to preserve the diversity of parties in smaller countries whose delegations require a certain minimum size. If the number of mandates were distributed in direct proportion to the population, Malta, for example, would not even qualify for a single seat. At the same time, the parliament's working capacity is guaranteed, which would not be the case with an equal weighting of the votes. Otherwise, the larger countries would send too many MEPs to Brussels, and parliament would be too big to operate effectively. The principle, therefore, largely limits larger countries from becoming overly dominant.

On the other hand, this principle contradicts the democratic tenet that every citizen's vote should be equal. Under the current arrangement, an MEP from a smaller country represents fewer citizens than an MEP from a larger country, giving people from smaller countries a greater voice. This contributes to a democratic deficit, a charge the European Union has often faced in the past.

What has changed with passage of the Lisbon Treaty?

When the Lisbon Treaty entered into force in December 2009, the total number of MEPs was increased from 736 to 750, plus the president. Each member state is allotted at least six seats, up to a maximum of 96. Germany, as the EU's most populous country with 80.5 million people, is given the highest number of seats, one for every 838,000 inhabitants. Malta, the EU's least populous country, with 412,655 inhabitants, has six seats in parliament, or one seat for every 68,775 people.

Following the last EU election in 2009, Germany - due to the vote being held under the provisions of the Treaty of Nice - was represented by 99 seats. Under the rules of the Lisbon Treaty, Germany loses three seats, but an interim arrangement has allowed Germany to hold on to these additional seats until the 2014 election.

What are the consequences of the Lisbon Treaty for the various countries?

With the Croatia joining the European Union in July 2013, the parliament's seats need to be re-distributed to provide representation for the newest member state.

Aside from Germany, 12 states - Austria, Belgium, Bulgaria, Croatia, the Czech Republic, Greece, Hungary, Ireland, Latvia, Lithuania, Portugal and Romania - will each lose a seat following the upcoming vote, in line with demographic changes. In this way, the new maximum number of parliamentarians will be maintained.

Could there be further changes in the future?

The European Parliament is already planning a new revision to the allocation of seats for the EU election in 2019. Changes in the number of member states, as well as demographic trends, must regularly be taken into account - the seats must continue to be distributed in an objective, fair and transparent manner.

Some MEPs have even called for a complete revision of the electoral law. One possibility would be the introduction of transnational lists, which would allow EU voters from Lapland to the southern shores of Cyprus to directly vote for MEPs from a common list. But a complete overhaul of the electoral system would require a change to the EU Treaty, and national governments have yet to find a consensus on that issue.