Obstruction of justice is an incredibly broad code section. Obstruction charges most often come up with a person questioned in an investigation, other than the target of the investigation, lies or misleads law enforcement. Think of the words in a Miranda warning “you have the right to remain silent, but anything you say can be used against you.” What you say could be used against you. The best advice is to remain silent and not talk with law enforcement unless you have a lawyer present.
Obstruction charges most often arise when law enforcement claims a person lied while being questioned in an investigation. Usually these charges are brought against someone other than the main suspect in an investigation. They can arise when a person intentionally tries to protect a suspect, such as providing a false alibi or giving misleading information about something a suspect did. They can also occur when a person destroys, alters or conceals evidence.
18 USC 111 – Obstruction of Justice
(a) In general.–Whoever–
(1) forcibly assaults, resists, opposes, impedes, intimidates, or interferes with any person designated in section 1114 of this title while engaged in or on account of the performance of official duties; or
(2) forcibly assaults or intimidates any person who formerly served as a person designated in section 1114 on account of the performance of official duties during such person’s term of service, shall, where the acts in violation of this section constitute only simple assault, be fined under this title or imprisoned not more than one year, or both, and where such acts involve physical contact with the victim of that assault or the intent to commit another felony, be fined under this title or imprisoned not more than 8 years, or both.
(b) Enhanced penalty.–Whoever, in the commission of any acts described in subsection (a), uses a deadly or dangerous weapon (including a weapon intended to cause death or danger but that fails to do so by reason of a defective component) or inflicts bodily injury, shall be fined under this title or imprisoned not more than 20 years, or both.