Since time immemorial human society has been in need of a power which would carry out control over it and prevent crime, punishing the culprit in case of offence. Nowadays this function is performed by the system of criminal justice which comprises police, as a means of law enforcement; courts, as organizations carrying out adjudication; and jails, prisons, probations and parole as kinds of corrections. Criminal justice agencies, which are represented by the police investigating crime, and the attorneys prosecuting the offenders, are expected to operate within the rule of law. However, it is not infrequent that while rendering justice, the aforementioned agencies happen to involve in certain ethical issues in cases leading to miscarriage of justice. It is the goal of the present paper to review such areas of ethical issues within the field of criminal justice as: pretexting during investigation and police misconduct, and their influence on the investigated case. When investigating a crime, it is often the case that certain information is obtained via pretexting — a trick which is described by Hartwell (2006) as “obtaining information through deception or false pretence”. The participants of pretexting misinterpret their identities or purposes in order to get information which otherwise might have not been revealed to them. Another case could be when a lawyer leading the case hires a third party to obtain evidence — such a party is called an “undercover investigator” (Hricik, 2007). On the whole, such techniques can help in advancing the investigation process and have proved to be successful. However, conducting a case with the use of pretexting and undercover investigators can raise a whole range of ethical issues and question the lawfulness and compliance of actions directed at obtaining information. There exists a set of Model Rules of Professional Conduct drawn up within the American Bar Association (2008) which can be used as guidelines in planning a proper investigation despite their inability to settle all the issues which might rise in course of the case. Otherwise there is a possibility of a retaliatory lawsuit alleging, inter alia, fraud and trespass. Another slippery ground in the course of investigation concerns the limits of police authority when carrying out their duty. There are frequent reports of police misconduct, with the most common claims brought against police officers being false arrest (or false imprisonment), malicious prosecution, and use of excessive or unreasonable force. According to the US Department of Justice (2008). “It is a crime for one or more persons acting under color of law willfully to deprive or conspire to deprive another person of any right protected by the Constitution or laws of the United States. … The types of law enforcement misconduct covered by these laws include excessive force, sexual assault, intentional false arrests, or the intentional fabrication of evidence resulting in a loss of liberty to another”. As a rule, it is quite impossible to prove police misconduct since there exists a code of non-disclosure among the police officers involved in a case of exceeding power. Moreover, occurrence