The purpose of the justice system should not be to give guilty people the best chance to stay out of prison.
Yes, if you're guilty, lying may be your best defense. That doesn't mean the justice system should encourage it! If you're guilty, the justice systems want you to go to jail. All the protections exist to protect innocent people.
You know, it would be terrible if I was found guilty of willful copyright infringement under the Digital Millennium Copyright Act, which carries "A fine of not more than $500,000 or imprisonment for not more than five years, or both, for the first offense"[1]. If I had committed such a terrible act as torrenting seven movies, the insult to my conscience would surely move me to accept the felony penalties with civic stoicism - after such twisted malice from myself, the additional moral consequences of pleading "Not Guilty" would be too great to bear.
[1] https://en.wikipedia.org/wiki/Copyright_law_of_the_United_St...
I'm not expressing an opinion on whether throwing someone in jail for torrenting movies is the right moral outcome. What I am saying is that a system which officially says "Yes, lying in court is legally permissible as long as you're lying about something related to a bullshit law" is not exactly sustainable.
I think the DMCA is a stupid and unfair law. The mafia probably thinks RICO is a stupid and unfair law. Someone who is a habitual drunk driver (but is convinced they can 'handle their liquor' better than the general public) probably thinks drunk driving laws are stupid and unfair. What of it?