Deputies of the European Parliament are elected on the term of five years. Each following election is held during the last year of a five year term mentioned above. The deputies are elected by citizens of the countries which are enlisted into the EU. In order to take part in the election process as an elector, a citizen is required to be registered as a candidate.
The deputies of the European Parliament (EP) fulfil their duties according to the principle of the "free mandate". It means that these people do not depend on the orders of their political fractions. It must be separately mentioned, that EP deputies have got a legal right to vote in person with no regard on their fractions' official decisions. They are not obliged to fulfil somebody's will and instructions. A "free mandate" can also be interpreted as complete independence of deputies from every citizen, since a deputy is supposed to represent a part of nation on the whole and not to follow the interests of a single person.
As a matter of fact, each EU country has got own algorithm of maintaining the election process in correspondence with basic norms of the EU legislation.