American prosecutors often treat the concept of obstruction of justice as if the concept only meant efforts to prevent them from successfully prosecuting a case. That concept of obstruction might be acceptable in a country like Nazi Germany or the Soviet Union, but it is not acceptable in the United States of America. The U.S. Constitution guarantees rights to American citizens accused of illegal actions.
A prosecutor who uses illegally obtained information in an
investigation is guilty of obstruction of justice. The
Constitution guarantees those accused of crimes the right to
confront their accusers in court because the British government had
allowed convictions based on anonymous claims that might have been
fabrications. Government agencies wanting to obtain information by
electronic eavesdropping must first obtain approval by a judge.
Eavesdropping information obtained without court
approval may be considered "fruit
of the poisonous tree" and thus unusable by the
prosecution. The courts may prevent prosecution of individuals
whose possible involvement in an activity is learned from "fruit of
the poisonous tree"