Question about legal documents

[CFS0700]

What is the name of your state (only U.S. law)? Illinois

Can an attorney knowingly lie in a legal document? And if they do and it harms someone what can the person do?

[las365]

You are going to have to be more specific to get anything resembling an accurate response.

What kind of document?
What was the alleged lie?
Who was negatively affected and how?

[CFS0700]

A motion to dismiss
It was written that my mother did something but she did not do it and can be proven.

It is devasting to my mother.

I don't want to go into to total details but what was written is an attack against her. It can be proven she did not do it. But what I read in a motion a attorney can write almost anything and say it is supporting a legal argument. is that true even if he or she knows it is a lie..?