25 U.S. Code § 2803 - Law enforcement authority
The Secretary may charge employees of the Bureau with law enforcement responsibilities and may authorize those employees to—
(2) execute or serve warrants, summonses, or other orders relating to a crime committed in Indian country and issued under the laws of—
(A) the United States (including those issued by a Court of Indian Offenses under regulations prescribed by the Secretary or offenses processed by the Central Violations Bureau); or
(3) make an arrest without a warrant for an offense committed in Indian country if—
(A) the offense is committed in the presence of the employee, 
(B) the offense is a felony and the employee has probable cause to believe that the person to be arrested has committed, or is committing, the felony;
(C) the offense is a misdemeanor crime of domestic violence, dating violence, stalking, or violation of a protection order and has, as an element, the use or attempted use of physical force, or the threatened use of a deadly weapon, committed by a current or former spouse, parent, or guardian of the victim, by a person with whom the victim shares a child in common, by a person who is cohabitating with or has cohabited with the victim as a spouse, parent, or guardian, or by a person similarly situated to a spouse, parent or guardian of the victim, and the employee has probable cause to believe that the person to be arrested has committed, or is committing the crime; or
(i) the offense involves—
(I) a misdemeanor controlled substance offense in violation of—
(bb) title IX of the Personal Responsibility and Work Opportunity Reconciliation Act of 1996 (21 U.S.C. 862a et seq.);  or
(4) offer and pay a reward for services or information, or purchase evidence, assisting in the detection or investigation of the commission of an offense committed in Indian country or in the arrest of an offender against the United States;
(5) make inquiries of any person, and administer to, or take from, any person an oath, affirmation, or affidavit, concerning any matter relevant to the enforcement or carrying out in Indian country of a law of either the United States or an Indian tribe that has authorized the employee to enforce or carry out tribal laws;
(8) when requested, assist (with or without reimbursement) any Federal, tribal, State, or local law enforcement agency in the enforcement or carrying out of the laws or regulations the agency enforces or administers.
 So in original. The comma probably should be a semicolon.
 See References in Text note below.
Source(Pub. L. 101–379, § 4,Aug. 18, 1990, 104 Stat. 475; Pub. L. 109–162, title IX, § 908(b),Jan. 5, 2006, 119 Stat. 3083; Pub. L. 111–211, title II, § 211(c),July 29, 2010, 124 Stat. 2266.)
References in Text
The Controlled Substances Act, referred to in par. (3)(D)(i)(I)(aa), is title II of Pub. L. 91–513, Oct. 27, 1970, 84 Stat. 1242, which is classified principally to subchapter I (§ 801 et seq.) of chapter 13 of Title 21, Food and Drugs. For complete classification of this Act to the Code, see Short Title note set out under section 801 of Title 21 and Tables.
The Personal Responsibility and Work Opportunity Reconciliation Act of 1996, referred to in par. (3)(D)(i)(I)(bb), is Pub. L. 104–193, Aug. 22, 1996, 110 Stat. 2105. Title IX of the Act enacted section 862b of Title 21, Food and Drugs, and sections 608a, 710, and 14016 of Title 42, The Public Health and Welfare, amended section 1693b of Title 15, Commerce and Trade, section 32 of Title 26, Internal Revenue Code, and sections 1396a, 1396g, 1397a, 1397b, 1437d, 1437f, and 1437z of Title 42, and enacted provisions set out as notes under section 32 of Title 26 and sections 601, 710, and 1396a of Title 42. For complete classification of this Act to the Code, see Short Title of 1996 Amendments note set out under section 1305 of Title 42 and Tables.
2010—Par. (2)(A). Pub. L. 111–211, § 211(c)(1), substituted “or offenses processed by the Central Violations Bureau); or” for “), or”.
Par. (3)(B), (C). Pub. L. 111–211, § 211(c)(2)(B), substituted “probable cause” for “reasonable grounds”.
Par. (3)(D). Pub. L. 111–211, § 211(c)(2)(A), (C), (D), added subpar. (D).
2006—Par. (3)(C). Pub. L. 109–162added subpar. (C).