Use this link to watch the oral argument in the Washington State Supreme Court in Guerra v Washington State (also known as In Re Guerra). This is the “faithless electors” case in which three Democratic presidential electors were each fined $1,000 for voting for someone other than Hillary Clinton.
The attorney for the electors made an analogy to a federal judge who had been appointed after telling the President that he or she would vote a certain way in a future case. He also made the analogy to U.S. Senators in the days when state legislatures appointed Senators, and in which the potential Senator promised the state legislature that he would vote a certain way.
The attorney for the state responded to a question about whether presidential electors might use a secret ballot in December when they are serving as electors. The attorney for the state said a secret ballot is impossible. However, at least one state has used secret ballots when presidential electors vote. Minnesota had secret ballots for electors in 2004. A Democratic presidential elector in 2004 voted for John Edwards for President instead of John Kerry. To this day, no one knows which elector voted that way. It has always been believed that the elector made an absent-minded clerical error, but no one can ask the elector because no elector has ever confessed to being the elector who did that. Thanks to Professor Derek Muller for the links to the two faithless elector hearings.