Methodology

Definition

We define a floor-crossing as any instance where a sitting member of a Canadian federal or provincial legislature formally changes party affiliation - or leaves to sit as an independent - without first resigning their seat and seeking a new mandate from voters.

Inclusion Criteria

A crossing is included when there is documentary evidence (Hansard records, official party announcements, credible news reporting, or academic sources) confirming the change of affiliation. Temporary suspensions or cases where an MP was expelled and did not join another caucus are noted but classified separately.

Categories

Each crossing is assigned one of eighteen categories that describe the primary motivation or character of the move. Categories range from ideological realignment and policy disagreement to opportunism, scandal, and strategic coalition-building. See each crossing's detail page for its assigned category.

Benefit Score

We assign a benefit score from 0 to 5 to every crossing, reflecting the degree to which the floor-crosser personally benefited from the move. The scale is defined as follows:

  • 0 - 0 - No benefit: The crosser's career ended or was significantly harmed.
  • 1 - 1 - Minimal benefit: No measurable gain; the crosser continued without improvement.
  • 2 - 2 - Slight benefit: Some modest positive outcome (e.g. minor committee role).
  • 3 - 3 - Moderate benefit: Clear career advancement or improved political standing.
  • 4 - 4 - Significant benefit: Major promotion such as a cabinet post or party leadership role.
  • 5 - 5 - Exceptional benefit: Transformative career outcome directly resulting from the crossing.

Sources

All data is sourced from parliamentary Hansard, Library of Parliament records, Elections Canada data, provincial legislature records, news archives (CBC, Globe and Mail, La Presse, and others), and relevant academic publications. Specific sources are cited on each crossing's detail page.

Limitations

Historical records are incomplete, especially for early Confederation-era provincial legislatures. Some crossings may be missing or imprecisely dated. Category and benefit score assignments involve editorial judgment and are open to revision. We welcome corrections and contributions.