1. By the common law, constables are said to have been conservators of the peace ; and in consequence of this cha racter, probably, every constable has un doubted authority to arrest all persous who commit an affray, assault, or breach of the peace in his presence, and keep them in safe custody until they can be brought before a magistrate. But as his duty is to preserve the peace, and not to punish for the breach of it, it is doubtful whether he can arrest by his own autho rity and without a warrant, upon the information or charge of a third person, for an affray committed in his absence. (See the case of Timothy v. Simpson, 1 Crompton, Meeson, and Roscoe's Reports, p. 760.) By the Metropolis Police Act, and the Municipal Corporation Reform Act, constables appointed under those acts are expressly authorised, in charges of petty misdemeanor in the night time, to take bail by recognizance for the appear ance of the offender before a magistrate within a limited time.
2. A constable having reasonable cause to suspect that a felony has been commit ted, may arrest and detain the supposed offender until he can be brought before a magistrate to have his conduct investigat ed; and he will be justified in so doing even though it should afterwards appear that in fact no felony was committed. In this case there is a distinction between the authority of a constable and that of a private person ; the former may arrest if he can show a reasonable ground of suspicion that a felony has been commit ted; but a private person, in order to justify himself for causing the imprison ment of another, must prove, in addition to the reasonable suspicion of the individual, that a felony has actually been committed. A constable is bound to arrest any person whom he sees committing a felony, or any person whom another positively charges with having committed a felony ; but generally speaking, he has no authority to arrest for a misdemeanor, either upon his own reasonable suspicion or the charge of another person, without a magistrate's warrant. With respect to the authority of a constable to arrest for felony or breach of the peace, Mr. Justice Buller is reported to have said, that " if a peace officer, of his own head, takes a person into custody on suspicion, he must prove that such a crime was committed ; but if he receives a person into custody on a charge preferred by another of felony or breach of the peace, then lie is to be con sidered as a mere conduit ; and if no felony or breach of the peace was com mitted, the person who preferred the charge alone is answerable." Lord Ellenborough, in the case of Hobbs v. Branscomb (3 Campbell's Reports, 420), said that "this rule appeared to be rea sonable." 3. Constables were authorised by the common law to arrest such "strange per sons as do walk abroad in the night season." (Lambard's Constable, p. 12.)
This authority, which was perhaps suffi ciently definite in times when the curfew was in practice and when watch and ward were kept, is at the present day of so vague a nature, that a peace-officer could scarcely act under it without danger of an action in every particular instance. It is, however, obviously essential to the efficiency of any system of police, that constables should be armed with some general authority of this nature, especially in towns. By the Metropolitan Police Acts (10 Geo. IV. c. 44, and 2 & 3 Viet. c. 47), it is provided that any man be longing to the police force appointed under these acts may apprehend all loose, idle, and disorderly persons whom he shall find disturbing the public peace, and any person charged by another with having recently committed an aggravated assault, or any person whom he shall have just cause to suspect of any evil designs, and all persons whom he shall find between sunset and the hour of eight in the morning lying in any highway, yard, or other place, or loitering therein, and not giving a satisfactory account of themselves, and deliver them to the con stable in attendance at the nearest watch house, to be secured until they can be brought before a magistrate. The con stable may detain persons, and vessels, and carriages conveying property sus pected to be stolen, &e. Offenders are to be taken to the nearest station-house, and the horses and carriages of offenders are to be detained. The Municipal Reform Act contains a similar but less compre hensive provision, authorising any _con stable appointed under that act, while on duty, to apprehend all idle and disorderly persons whom he shall find disturbing the public peace, or whom he shall have just cause to suspect of intention to commit a felony. The constable of a municipal borough under the act has power within any part of the county to which the borough belongs, and also within every other county within seven miles of such borough. Besides the specific authorities which apply to the metropolitan police district and the boroughs affected by the Municipal Reform Act, there is no doubt that in general a constable, by virtue of his common-law authority, may stop any person carrying by night a bundle or goods under circumstances of reasonable suspicion; and if upon examining him his suspicions are not removed, he may detain him in his custody. A constable has also a general authority to apprehend for offences against the Vagrant Act, 4 & 5 George IV. c. 83, or against the Larceny Act, or the Malicious Injuries Act, 7 & 8 George IV. c. 29 and 30.