Oetjen joined the FDP in 1995. He first became a member of the State Parliament of Lower Saxony in the 2003 state elections, and was subsequently re-elected three times. From 2003 until 2011, he served as his parliamentary group's spokesperson on agriculture policy.
Member of the European Parliament, 2019–present
In October 2018, Oetjen was elected candidate for the 2019 European elections by his party. In parliament, he is active in the following committees and delegations in various functions:
DMAS - Delegation for relations with the Mashreq countries
In addition to his committee assignments, Oetjen is also a member of the European Parliament Intergroup on Anti-Racism and Diversity[2] and the European Parliament Intergroup on Seas, Rivers, Islands and Coastal Areas.[3]