Analysis
Evidence supports that economic and political systems often favor the wealthy (e.g., campaign finance, lobbying), but 'rigged' implies intentional, uniform bias, which is harder to prove. Structural barriers (e.g., voter suppression, gerrymandering) disproportionately affect marginalized groups, but the system also allows for reform and accountability.
Background
Sanders frequently criticized income inequality, corporate influence in politics, and the 2016 primary process (e.g., superdelegates) as examples of systemic bias. Studies show wealth gaps and political representation disparities, but debates continue over causality and solutions.
Verdict summary
Sanders' claim reflects systemic inequalities but oversimplifies the complexity of political and economic structures.