The threats have to be something that will really affect them. However, the strictest threat is no hindrance if it's not carried out when someone says it will be. Don't leave an open ended time period.
Anybody who has effectively dealt with people in a supervisory capacity knows this. If you say you are going to do something punitive, then do it. Otherwise don't even say it. That will undermine anything else you say.
(This isn't aimed at Senator Dorgan. It's aimed at the regulators who let eleventy billion violations slide, and those without the courage to put some teeth into any punishment among others. Senator Dorgan has been warning people of the financial consequences all along.)
and it didn't do any good!