This quote is from the same source as my post and quotes in 'Debunking Police Evidence'
“Police Error (PE) and Misconduct
Police officers or detectives are often the first members of the criminal
justice system to intervene in a criminal case and become involved at a very
critical time—the beginning. The activities of the police at this juncture and
how well they do their job can have dramatic implications for an innocent
individual who has become a suspect. Prosecutors, when making a decision
concerning whether to prosecute a case, rely heavily on the evidence pre-
sented to them by police officials. Evidence properly collected by police
should be able to be properly reviewed by prosecutors. However, when
police conduct sloppy investigations or manufacture evidence (e.g., the
Rampart scandal3) or produce mistaken eyewitness identification because
of biased identification techniques (e.g., misuse of show ups or conducting
biased photospreads or lineups), prosecutors may make decisions to use
such evidence without full knowledge of how it was acquired. Thus, once
PE or misconduct contributes to a wrongful arrest, there is an increased
likelihood that other criminal justice officials will add momentum to the
mistake. Huff et al. (1996) call this phenomenon the ratification of error:
The criminal justice system, starting with the police investigation of an alleged
crime and culminating in the appellate courts, tends to ratify errors made at
the lower levels of the system. The further the case progresses in the system,
the less chance there is that the error will be discovered and corrected, unless
it involves a basic issue of constitutional rights and due process. (p. 144)
For example, Leo and Ofshe (1997-1998) found that police-induced
false confessions substantially bias jury evaluations of evidence and are per-
ceived as dispositive of issues of guilt (see also Gross, 1996, 1998).
Extant research confirms that PE and misconduct are significant contribu-
tors to the wrongful conviction of the innocent (Conners et al., 1996; Gross
et al., 2005; Huff et al., 1986, 1996; Leo & Ofshe, 1997-1998; McCloskey,
1989; Radelet et al.,1992; Scheck et al., 2000; Yant, 1991).4
Prosecutorial Error (PrE) and Misconduct
Prosecutorial error or misconduct is another factor associated with wrong-
ful conviction (see Buckley v. Fitzsimmons, 1993; Miller v. Pate, 1967). The
prosecutor is considered by many to be the most powerful individual within
the criminal justice process (Gershman, 1999; Gottfredson & Gottfredson,
1988). Because of their position within the criminal justice process, prose-
cutors’ errors or misconduct can result in devastating consequences to an
innocent suspect (Huff et al., 1996; Leo & Ofshe, 1997-1998). Prosecutors,
who enjoy significant immunity, have wide discretion regarding how many
investigative resources to use, which cases to dismiss, and which cases to
prosecute. By deciding to dismiss a case believed to be based on unreliable
evidence (e.g., a false confession, misidentification) or where there exists
trustworthy exculpatory evidence, prosecutors can correct errors of other
system participants. On the other hand, when a prosecutor pursues a case
based on bias, limited information, or less than reliable evidence, a wrong-
ful conviction can occur.
”
www.sagepub.com/spohnstudy/articles/1/Ramsey.pdf