Partisan differentiation in legislative texts in South Korea: Agenda selection, framing, and partisan classifiability in the 21st national assembly

How do parties translate their ideological identities into the language of legislation? This study analyzes 22,964 member-sponsored bills from the Democratic Party of Korea and the People Power Party in the 21st Korean National Assembly, decomposing partisan differences into three dimensions: agenda setting, framing, and partisan classifiability. The study finds significant divergence in topic distributions across parties, with the Democratic Party prioritizing judicial reform and labor rights while the People Power Party emphasizes real estate taxation and regional development. More substantively novel is the evidence for within-topic framing differences: even after agenda composition is held constant, keyword contrasts within shared policy domains reveal recurring asymmetries in problem diagnosis and justificatory language. A text-only classification model further confirms that partisan identity is consistently encoded in legislative texts. These findings indicate that agenda selection and within-topic framing combine to produce a consistent partisan signal. Party discipline, decentralized incentives for position-taking, and ideological polarization constitute plausible institutional and political conditions under which such a pattern may emerge, with broader implications for comparative research on party-centered democracies.