Methodology

What counts as a floor crossing

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. This includes MPs, MPPs, MLAs, MNAs, and MHAs.

What we include

A crossing is included when there is documentary evidence: Hansard records, official party announcements, credible news reporting, or academic sources confirming the change. Temporary suspensions and expulsions where the member did not join another caucus are noted but classified separately.

How we categorize

Each crossing is assigned a category describing the primary motivation — from policy disagreement and ideological realignment to opportunism, scandal, and coalition-building. These are editorial judgments, clearly labelled, and open to revision.

Benefit score

Every crossing receives a score from 0 to 5 reflecting how much the crosser personally benefited from the move:

• 0 - Career destroyed. They lost everything.
• 1 - No measurable gain. Career continued unchanged.
• 2 - Modest benefit. A minor committee role or appointment.
• 3 - Clear advantage. A promotion or improved political standing.
• 4 - Major payoff. Cabinet post or party leadership role.
• 5 - Maximum reward. Got exactly what they wanted.

Our sources

Parliamentary Hansard, Library of Parliament records, Elections Canada, provincial legislature records, news archives (CBC, Globe and Mail, La Presse, and others), and peer-reviewed academic publications. Specific sources are cited on every crossing's detail page.

What we might be missing

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. If you know of a crossing we missed, we welcome corrections and contributions.