The functions of justice, and those of the police, must be apt in many points to run one into another: especially as the business would be very badly managed if the same persons, whose more particular duty it is to act as officers of the police, were not upon occasion to act in the capacity of officers of justice. The ideas, however, of the two functions may still be kept distinct: and I see not where the line of separation can be drawn, unless it be as above.

As to the word police, though of Greek extraction, it seems to be of French growth: it is from France, at least, that it has been imported into Great Britain, where it still retains its foreign garb: in Germany, if it did not originate there, it has at least been naturalized. Taken all together, the idea belonging to it seems to be too multifarious to be susceptible of any single definition. Want of words obliged me to reduce the two branches here specified into one. Who would have endured in this place to have seen two such words as the phthano-paranomic or crime-preventing, and the phthano-symphoric or calamity-preventing, branches of the police? the inconveniences of uniting the two branches under the same denomination, are however, the less, inasmuch as the operations requisite to be performed for the two purposes will in many cases be the same. Other functions, commonly referred to the head of police, may be referred either to the head of that power which occupies itself in promoting in a positive way the increase of the national felicity, or of that which employs itself in the management of the public wealth. See infra, liv. note.

IPML Chapter 16 Section 2 Part 2