What is Obstruction Of Justice?

Legal Definition
The crime of obstruction of justice, in United States jurisdictions, refers to the crime of obstructing prosecutors or other (usually government) officials. Common law jurisdictions other than the United States tend to use the wider offense of perverting the course of justice.
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Legal Definition
Obstruction of justice is defined in the omnibus clause of 18 U.S.C. § 1503, which provides that "whoever . . . . corruptly or by threats or force, or by any threatening letter or communication, influences, obstructs, or impedes, or endeavors to influence, obstruct, or impede, the due administration of justice, shall be (guilty of an offence)." Persons are charged under this statute based on allegations that a defendant intended to intefere with an official proceeding, by doing things such as destroying evidence, or intefering with the duties of jurors or court officers.

A person obstructs justice when they have a specific intent to obstruct or interfere with a judicial proceeding. For a person to be convicted of obstructing justice, they must not only have the specific intent to obstruct the proceeding, but the person must know (1) that a proceeding was actually pending at the time; and (2) there must be a nexus between the defendant’s endeavor to obstruct justice and the proceeding, and the defendant must have knowledge of this nexus.

§ 1503 applies only to federal judicial proceedings. Under § 1505, however, a defendant can be convicted of obstruction of justice by obstructing a pending proceeding before Congress or a federal agency. A pending proceeding could include an informal investigation by an executive agency.
Legal Definition
The noncompliance with the legal system by interfering with (1) the law administration or procedures, (2) not fully disclosing information or falsifying statements, and (3) inflicting damage on an officer, juror or witness.