How about using Session's own words about lying under oath:
It has been proven beyond a reasonable doubt and to a moral certainty that William Jefferson Clinton perjured himself before a Federal grand jury and has persisted in a continuous pattern of lying and obstructing justice. The chief law-enforcement officer of the land, whose oath of office calls on him to preserve, protect and defend the Constitution, crossed the line and failed to defend and protect the law and, in fact, attacked the law and the rights of a fellow citizen. Under our Constitution, equal justice requires that he forfeit his office. For these reasons, I felt compelled to vote to convict and remove the President of the United States from office.
It is crucial to our system of justice that we demand the truth. I fear that an acquittal of this President will weaken the legal system by providing an option for those who consider being less than truthful in court. Whereas the handling of the case against President Nixon clearly strengthened the nation's respect for law, justice and truth, the Clinton impeachment perjury may unfortunately have the opposite result.
Seems pretty cut and dry to me.