Seif's thematic areas of expertise in the committee are basic rights; EU citizenship; coordination between the judicature and police; border protection and counterterrorism; and asylum- and migration policy.

European Affairs On 17 July 2015, Seif voted against his party's line and rejected the Merkel government’s proposal to negotiate a third bailout for Greece.

[5][6] As the EU deputy spokesperson for the CDU/CSU parliamentary group and rapporteur for affairs in Great Britain, Seif is outspoken on the topic of Brexit.

[14] Following Germany's September 2017 federal elections, Seif identified points of contention between the CDU, CSU, and SPD, telling Reuters that pensions, Europe and asylum and migration policy were all “areas where there are explosives built into the coalition agreement.

[16] Ahead of the Christian Democrats’ leadership election, Seif publicly opposed in 2020 Friedrich Merz's candidacy to succeed Annegret Kramp-Karrenbauer as the party's chair.