Andrew Harnik/AP

In his opening statement to the House intelligence committee, Special Counsel Robert Mueller clarified an answer he gave to Rep. Ted Lieu.

His original answer was seen as Mueller saying the only reason the President was not indicted was because, as president, he cannot be indicted.

However, Mueller clarified the correct view is that they made no assessment as to whether there was a crime or not because of the OLC guidance.

"Now before we go to questions, I want to add on correction to my testimony this morning. I want to go back to one thing that was said this morning by Mr. Lieu who said, and I quote, you didn't charge the President because of the OLC opinion. That is not the correct way to say it," Mueller said.

Mueller then corrected Lieu's wording: "As we say in the report, and as I said at the opening, we did not reach a determination as to whether the President committed a crime. With that, Mr. Chairman, I'm ready to answer questions."

What you need to know about the OLC opinion: Internal Justice Department policies say that a sitting president cannot be indicted. The policy comes from the OLC — the Office of Legal Counsel — and it dates back to the Nixon administration. It is binding on all Justice Department employees, including Mueller and his team of prosecutors.

In his report, Mueller directly explained how this had a major impact on his internal deliberations.

In effect, Mueller framed his entire obstruction investigation around the notion that he couldn't bring any charges against Trump, even if he found ironclad evidence against him, because of the OLC opinion.