Are plea bargains unconstitutional?

Is plea bargaining unconstitutional? An article published by the Cato institute lays out a strong argument that it is. The essence of the problem is this: when the accused do not accept plea bargains, but insist on exercising their rights to trial by jury, prosecutors often threaten to charge the accused with even greater crimes, with more severe penalties. Accused persons should not be penalized for exercising their Constitutional rights. To do so is an abuse of prosecutorial discretion. Follow the link below to view the Cato Institute article.

http://www.cato.org/pubs/regulation/regv26n3/v26n3-7.pdf