1. State laws in many states bind the delegates to vote as pledged.
2. Convention rules from previous conventions bind delegates to vote as pledged (going so far as to eject delegates who don’t vote as required and then record their votes as if they voted as directed).
To some extent, neither of the above matters. The rules are rewritten to some extent each convention, and the establishment could mess with the rules and ignore GOP voters if they chose to. I know there would be a penalty, but insiders might not care. That is why Trump needs to pay attention to choosing loyal delegates.
1. State laws in many states bind the delegates to vote as pledged. True and in PA only 17 of the 50 are bound. the rest free to vote for reagan if they want.