Can individuals access classified national security information without having undergone the background investigation process and been granted a security clearance? Normally the answer is no, but there are certain instances where the requirement is waived. Here are some of the exceptions:
The President and members of the U.S. Senate and House of Representatives do not undergo the normal background investigation process and are not granted security clearances. They may be granted access to classified information relating to matters under the jurisdiction of the respective committees to which they are assigned and if access is needed to perform their duties in connection with such assignments. This does not apply to their staff members, who are required to undergo the investigation and clearance process just like everyone else.