Abstract

DIAZ DOMINGUEZ, Alejandro. Ideal Points in Mexico’s Congress: ¿Individual Traits or Partisan Ties?. Bol. Mex. Der. Comp. [online]. 2025, vol.58, n.173, e20069.  Epub June 22, 2026. ISSN 2448-4873.  https://doi.org/10.22201/iij.24484873e.2025.173.20069.

This study analyzes the ideological positions of members of the Mexican Cham ber of Deputies from 2009 to 2015 by estimating ideal points. It explores whether these posi tions are primarily explained by party affiliation or by individual characteristics such as gender, Single Member District legislators, and previous status as substitute legislators. The wnominate scaling method was applied to non-unanimous roll-call votes from legislatures LXI, LXII, and LXIII to estimate ideal points in a two-dimensional space. Then, linear models were used to examine the distance between each legislator and their party’s average position. Party affilia tion strongly predicts ideological placement. However, female deputies, majority rule elected members, and former substitutes show distinct patterns of proximity or distance to their par ty lines, varying by conflict dimension and legislature. The emergence of a new anti-system party (Morena) significantly shifts the political spectrum by positioning itself in opposition to the ruling party. The study is based on a limited sample of votes and legislative periods, which restricts generalizability. Nevertheless, it offers valuable insights into legislative behav ior in Mexico and points to future research on the role of other personal attributes in shaping political representation.

Keywords : Mexico; congress; ideal points; gender; deputies..

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