This act was passed during the reign of William III. The main purpose behind the statute was to make some corrections to the Offences at Sea Act 1536. These changes included allowing for acts of piracy to be “examined, inquired of, tried, heard and determined, and adjudged in any place at sea, or upon the land, in any of his Majesty’s islands, plantations, colonies, dominions, forts, or factories”. This enabled admirals to hold a court session to hear the trials of pirates in any place they deemed necessary, rather than requiring that the trial be held in England, thus avoiding the costly and time-consuming transport of captured pirates across the Atlantic. It also meant those accused of piracy didn’t necessarily have to be tried by a jury.
In addition, the act expanded the legal definition of piracy as a capital crime to include any subject of the crown who commited any act of piracy “under colour of any commission from any foreign prince or state”, meaning those serving as privateers for a foreign power were now considered pirates. It was also now considered a piracy if any commander stole the ship, even if no piratical acts were intended. The act also added the offence of being an accessory to piracy, which was aimed at those who fenced and purchased their stolen goods, thus undermining their support.
The act was made perpetual by section 3 of the Perpetuation, etc. of Acts 1719.
You can read the full act or download it at www.legislation.act.gov.au.