A federal judge has ruled that the Colorado Republican Party cannot block unaffiliated voters from participating in the state's primary elections. The judge found that the party failed to show evidence that the semi-open primary system would have an outcome-determinative effect on the party's nominees and thus doesn't impose a severe burden on its associational rights. Colorado's 2016 Proposition 108 allows for semi-open primary elections with unaffiliated voters participating. There are more than 1.8 million unaffiliated voters in the state, and the ruling is likely to be appealed.