A more thorough explanation:

Catchpoll (kach-pohl) is a historical term used to refer to a sheriff's deputy or bailiff. It was also spelled as catchpol or catchpole. In ancient times, it was used without any negative connotation for people who arrested others on any legal action.

For example, Thomas Blount in his book Nomo-Lexicon: A Law-Dictionary (1670) wrote, "Catchpol ... (One that catches by the Poll) Though now taken as a word of Contempt, yet in ancient times, it was used, without reproach, for such as we now call Sergeants of the Mace, Bailiffs, or any other that use to Arrest Men upon any Action."

This means that catchpoll was a term used to describe people who were authorized to arrest others on legal grounds. However, over time, the term catchpoll became associated with negative connotations and was used as a word of contempt.

Overall, catchpoll was a term used in the past to describe a law enforcement officer who had the authority to arrest people on legal grounds.