Is Plea Bargaining Ethical ?

Been following this story and I am concerned about the use of plea bargaining..

South Africa's criminal prosecution service has held out the prospect of medical parole if Xolile Mngeni, pleads guilty and agrees to give evidence against Shrien Dewani, who is accused of commissioning her murder.

If the alleged hitman - who has brain cancer - takes up the offer he would become the fourth member of the gang to receive a substantial sentence benefit in return for helping the police.

It would also mean that all four South African alleged conspirators to Mrs Dewani's murder would have been lined up to testify against her husband, whom the South African authorities have named as the plot's mastermind.

Mr Dewani, 33, a businessman from Westbury-on-Trym, near Bristol, insists he is innocent. His supporters have previously claimed he is being "stitched up" by a police force trying to protect its country's tourist industry by portraying his wife's murder as orchestrated by a foreigner

http://www.telegraph.co.uk/news/worldnews/africaandindianocean/southafri...