Answer to Question 1
Despite the immunity they enjoy, there is recourse for dealing with overzealous prosecutors.
Such consequences may include:
Private admonition or reprimand
Public reprimand
Suspension from law practice
Permanent disbarment
In the case of an elected district attorney, being thrown out of office
Answer to Question 2
If an individual is targeted for prosecution merely because he or she is a member of a certain group, such as being a minority, then his or her constitutional rights may be violated.
This is known as selective prosecution.
In Oyler v. Boles, 368 U.S. 448 (1968), the Court held that the prosecution's selection of cases violates the equal protection clause only when it is intentional and is intended to target a certain class of cases . . . or specific persons. In that case, the defendant presented evidence that he was the only individual of six sentenced under a particular statute. The Court held that this was not discriminatory because the defendant was unable to demonstrate intent by the prosecutor or provide evidence that he fit the group targeted for prosecution.
If a prosecutor's charging decision is motivated by revenge, then the resulting charge violates the due process clause of the Fourteenth Amendment. Specifically, if a prosecutor charges an individual simply because he or she is exercising his or her constitutional rights, such vindictive prosecution will not be allowed.
In Blackledge v. Perry, 417 U.S. 21 (1974), the defendant was convicted in a lower court for misdemeanor assault with a deadly weapon. The defendant filed an appeal with the county superior court for a trial de novo (a new trial), which is sometimes permitted in