We can try a criminal case with the slimmest possible amount of information. Why is bad faith action not criminal in modern democracy. It amounts to fraud of the highest degree. To me the most blatant form is those elected representatives who changed political party after election, but includes any elected official acting contrary to the platform they were elected on.
Democracy cannot survive this kind of fraud.
You’re thinking of Fiduciary Duty
For example, certain kinds of financial advisers have a fiduciary duty - that is, a duty to act in the best interests of their clients. But the ones with whom mere mortals interact are (quite predatory) salesmen.
In the same vein, I expect politicians do act in good faith towards their larger donors, but don’t see themselves as owing anything to their constituents.
I think elected officials, especially lawmakers, should be criminally liable for betraying the best interest of their constituents as laid out during their campaign.
How could this go wrong?