two different federal perjury statutes and under one of them, if you come in and recant before you are charged, it can be a defense and also, people at the grand jury are told, if you misremember something, or need to change your testimony, you can contact the prosecutor. it is difficult to charge and convict somebody for perjury. it has got to be clear-cut. there is a thing called true but misleading statement. something that is literally true even if it is misleading is not perjury. >> if the president were to lie to mueller in a voluntary interview which in and of itself were to be a crime, could that end up with the president being compelled to testified before a grand jury. >> i think the president could be compelled to testify in front