The biased use of enforcement discretion, such as that based on racial prejudice or corruption, is usually considered a legal abuse and a threat to the rule of law.
In some cases, selective enforcement may be desirable.... In other cases, selective enforcement may be inevitable....
In the United States federal system, the prosecutor has wide latitude in determining when, who, how, and even whether to prosecute for apparent violations of federal criminal law. The prosecutor's broad discretion in such areas as initiating or forgoing prosecutions, selecting or recommending specific charges, and terminating prosecutions by accepting guilty pleas has been recognized on numerous occasions by the courts...