Hi, I am Dzenana Hadziomerovic, an attorney from Sarajevo, BiH. It is interesting to hear the US experience. I would also like to refer to the ECHR case law ( as established in the case Natsvlishi and Tognidze v Georgia dated 29 April 20014)
"The Court .. notes that it can be considered a common feature of European criminal justice systems for an accused to obtain the lessening of charges or receive a reduction of his or her sentence in exchange for a guilty or nolo contendere plea in advance of trial or for providing substantial cooperation with the investigative authority (see the comparative legal study, paragraphs 62-75 above; see also, in this connection, Slavcho Kostov v. Bulgaria, no. 28674/03, § 17, 27 November 2008, and Ruciński v. Poland, no. 33198/04, § 12, 20 February 2007). There cannot be anything improper in the process of charge or sentence bargaining in itself (see, mutatis mutandis, Babar Ahmad and Others v. the United Kingdom (dec.), nos. 24027/07, 11949/08 and 36742/08, ECHR 6 July 2010). In this connection the Court subscribes to the idea that plea bargaining, apart from offering the important benefits of speedy adjudication of criminal cases and alleviating the workload of courts, prosecutors and lawyers, can also, if applied correctly, be a successful tool in combating corruption and organised crime and can contribute to the reduction of the number of sentences imposed and, as a result, the number of prisoners.
91. The Court considers that where the effect of plea bargaining is that a criminal charge against the accused is determined through an abridged form of judicial examination, this amounts, in substance, to the waiver of a number of procedural rights. This cannot be a problem in itself, since neither the letter nor the spirit of Article 6 prevents a person from waiving these safeguards of his or her own free will (see Scoppola v. Italy (no. 2) [GC], no. 10249/03, § 135, 17 September 2009). The Court observes in this connection that as early as in 1987 the Committee of Ministers of the Council of Europe called upon the member States to take measures aimed at the simplification of ordinary judicial procedures by resorting, for instance, to abridged, summary trials (see paragraph 54 above). However, it is also a cornerstone principle that any waiver of procedural rights must always, if it is to be effective for Convention purposes, be established in an unequivocal manner and be attended by minimum safeguards commensurate with its importance. In addition, it must not run counter to any important public interest (see, amongst other authorities, Scoppola (no. 2), cited above, § 135-36; Poitrimol v. France, 23 November 1993, § 31, Series A no. 277-A; and Hermi v. Italy [GC], no. 18114/02, § 73, ECHR 2006‑XII). "
I hope this may help!!