The most relevant one to Janus is the fact that you can't choose which union your dues go to - but you have a number of choices about how to feed yourself with your dollars. You can go to a restaurant; go to Smart & Final; go to Whole Foods; in general, those dollars are fungible and decisions about how they are spent are made by you, not by the state. In contrast, your only options with a union are to either attempt to influence union leadership as a member (which, by definition, every member with differing opinions cannot succeed at) or to switch jobs. For example. let's say you're a prison guard in California (and a member of the CCPOA), but you disagree with your union's lobbying and donations to increase prison sentences for non-violent drug offenders. Ostensibly, this is negotiation you are benefiting from, and fully within the responsibilities of a union. Union dues aren't really your money.