Which political theory has been interpreted to mean that a president can shield critical information from congress as a result of the separation of powers?

It´s executive privilege.

Explanation:

The supporter of the president´s executive privilege say that he can shield sensitive information from Congress if there´s a risk to national security, or his acts to preserve US national security exempt him from legal liability, enjoying legal immunity.

this is not a question its simply asking you to read and write a few sentences and   the question on the bottom its fairly easy, you can do this!