Kentucky Statutes on point when an Officer can arrest.
KRS 431.005 Arrest by peace officers – By private persons
(1) A peace officer may make an arrest:
(a) In obedience to a warrant; or
(b) Without a warrant when a felony is committed in his or her presence; or
(c) Without a warrant when he or she has probable cause to believe that the person being arrested has committed a felony; or
(d) Without a warrant when a misdemeanor, as defined in KRS 431.060, has been committed in his or her presence; or
(e) Without a warrant when a violation of KRS 189.290, 189.393, 189.520, 189.580, 511.080, or 525.070 has been committed in his or her presence, except that a violation of KRS 189A.010 or KRS 281A.210 need not be committed in his or her presence in order to make an arrest without a warrant if the officer has probable cause to believe that the person being arrested has violated KRS 189A.010 or KRS 281A.210; or
(f) Without a warrant when a violation of KRS 508.030 has occurred in the emergency room of a hospital without the officer’s presence if the officer has probable cause to believe that the person being arrested has violated KRS 508.030. For the purposes of this paragraph, “emergency room” means that portion of a licensed hospital which as the primary purpose of providing emergency medical care, twenty-four (24) hours per day, seven (7) days per week, and three hundred sixty-five (365) days per year.
(2) (a) Any peace officer may arrest a person without warrant when the peace officer has probable cause to believe that the person has intentionally or wantonly caused physical injury to a family member or member of an unmarried couple.
(b) For the purposes of this subsection, the term "family member" has the same meaning as set out in KRS 403.720(2).
(c) For the purpose of this subsection, the term "member of an unmarried couple" has the same meaning as set out in KRS 403.720(4).
EDITOR’S NOTE: The Kentucky Court of Appeals ruled that “member of an unmarried couple” includes homosexual couples, but not roommates unless engaged in an intimate (i.e., sexual) relationship. Ireland v. Davis, 957 S.W.2d 310 (Ky Ct. App. 1997).
(3) A peace officer may arrest a person without warrant when the peace officer has probable cause to believe that the person is a sexual offender who has failed to comply with the Kentucky Sex Offender Registry requirements based upon information received from the Law Information Network of Kentucky.
(4) For purposes of subsections (2) and (3) of this section, a "peace officer" is an officer certified pursuant to KRS 15.380.
(5) If a law enforcement officer has probable cause to believe that a person has violated a condition of release imposed in accordance with KRS 431.064 and verifies that the alleged violator has notice of the conditions, the officer shall, without a warrant, arrest the alleged violator whether the violation was committed in or outside the presence of the officer.
(6) A private person may make an arrest when a felony has been committed in fact and he has probable cause to believe that the person being arrested has committed it.
(7) If a law enforcement officer has probable cause to believe that a person has violated a restraining order issued under KRS 508.155, then the officer shall, without a warrant, arrest the alleged violator whether the violation was committed in or outside the presence of the officer.
KRS 431.015 Citation for misdemeanor – Arrest for certain misdemeanors - Failure to appear
(1) (a) KRS 431.005 to the contrary notwithstanding, and except as provided in paragraphs (b), (c), and (d) of this subsection, a peace officer shall issue a citation instead of making an arrest for a misdemeanor committed in his or her presence, if there are reasonable grounds to believe that the person being cited will appear to answer the charge. The citation shall provide that the defendant shall appear within a designated time.
(b) A peace officer may make an arrest instead of issuing a citation for a misdemeanor committed in his or her presence if the misdemeanor is:
1. A violation of KRS Chapter 508, 510, or 527, or KRS 189A.010;
2. An offense in which the defendant poses a risk of danger to himself, herself, or another person; or
3. An offense in which the defendant refuses to follow the peace officer’s reasonable instructions.
(c) A peace officer shall make an arrest for violations of protective orders issued pursuant to KRS 403.715 to 403.785.
(d) A peace officer may make an arrest or may issue a citation for a violation of KRS 508.030 which occurs in the emergency room of a hospital pursuant to KRS 431.005(1)(f).
(2) A peace officer may issue a citation instead of making an arrest for a violation committed in his or her presence but may not make a physical arrest unless there are reasonable grounds to believe that the defendant, if a citation is issued, will not appear at the designated time or unless the offense charged is a violation of KRS 189.223, 189.290, 189.393, 189.520, 189.580, 235.240, 281.600, 511.080, or 525.070 committed in his or her presence or a violation of KRS 189A.010, not committed in his or her presence, for which an arrest without a warrant is permitted under KRS 431.005(1)(e).
(3) If the defendant fails to appear in response to the citation, or if there are reasonable grounds to believe that he or she will not appear, a complaint may be made before a judge and a warrant shall issue.
(4) When a physical arrest is made and a citation is issued in relation to the same offense the officer shall mark on the citation, in the place specified for court appearance date, the word “ARRESTED” in lieu of the date of court appearance.