The weakness of freedom of speech is it also allows freedom of lying. It's the cost of it. I think there could/should be an amendment to constitution that prevents government officials from consciously lying to people
The fact of whether an official "consciously lying to people" is extremely hard to know, because it is a measure of someone's status of mind in the past. The real world is much more complicated than what you could imagine.
Good points. Clearly there are gray areas. But sometimes it would be possible to prove lying. Just like it is possible to prove some marketing is fraudulent.
Take Obama's: 'If you like your health care plan, you'll be able to keep your health care plan' as an example. He repeated this message for many many times: https://www.politifact.com/obama-like-health-care-keep/
How do you objectively decide:
1) Is this statement true?
2) Did he lie about it?
Also, how do you handle "if there is something I should not know, do not tell me"?