I don't get why you're being downvoted. Politicians should be held accountable for their tax-funded actions in their official capacity. If any lawmaker proposed a bill which was made law, and then found to be unconstitutional, they should be subject to legal penalty for violating the rights of the people they are charged with governing. Why is that a controversial though for some? We encourage further violations of rights by not having such rules in place.

I don't think it's qualified immunity, though, for policy makers it is usually referred to as legislative immunity.