I think it is interesting to view the mess with Libby through the lens of President Clinton. President Clinton had lots of experience with pardons and at least a little bit of experience with perjury. Let me explain.
Libby's perjury consisted in making false statements to a grand jury. Clinton also made false statements to a grand jury. One was prosecuted, one was not. It is obvious from Clinton's statements preceding and during his impeachment that his perjury was not a big enough deal to warrant all the fuss. Lying is lying, and when one lies to a grand jury, the law provides consequences. Clinton faced political consequences; Libby faced criminal ones. In my opinion, neither of these men would have been tried but for the offices they held; therefore, I think political remedies are more wise and appropriate. However, both men appear to have broken the law. I am not defending either on legal grounds.
My "defense" of Libby and of Clinton is that the special prosecutor system is prone to excess. The presence of so much political pressure leads to indictments that would otherwise not issue.
But don't take my word for it. President Clinton wrote an extensive defense of the 450 pardons he made during his tenure. He wrote that "[i]n some cases, I granted pardons because I felt the individuals had been unfairly treated and punished pursuant to the Independent Counsel statute then in existence." In other words, he saw the convictions of some people as unjust because of the process by which they were investigated, indicted, and prosecuted.
I'm not here to support or attack President Clinton or Scooter Libby. I don't know if Libby's sentence should have been commuted. I don't know if President Clinton should have been indicted. I am too ignorant of the underlying facts.
But it does seem to me that one standard should apply to both men, since their conduct seems substantially similar. And one standard should apply to both Presidents when they make their pardoning decisions.
I am not getting the impression that one standard governs.