To sue, to take someone to court in a legal disagreement.
They broke our contract and didn't pay, so we sued them and won.
She sued her employer for firing her, but she lost because they had the right to fire her.
To restrict, to put limits on something.
This is a restricted area, so stay away.
We need to restrict them from talking to anyone about our project.
To negotiate, to deal with or bargain with others to reach an agreement.
Instead of starting a war, we should negotiate and find a way to compromise.
We are trying to negotiate a better deal, but it isn't easy.
Responsible for or responsible to, to be responsible for something means to have the job of getting it done or taking care of.
If you are responsible to someone, it means that you are working under their control.
Oversee or supervise, to control or direct a process or project.
One of his responsibilities was to supervise the rescue operations and keep things under control.
As product manager, she oversees the work of several departments.
(We have many responsibilities, but she is the one responsible for product development.)
