It was not until 1689 that Privateering became internationally recognised when William III repudiated the neutral status of the Channel Islands which had been conferred by a Papal Bull of Sixtus IV in 1483 and allowed Letters of Marque to be issued to any person whose property had been seized by an enemy in order that they might have some chance of recouping their losses. Prizes had to be brought back to the privateer's port of registration where they were the subject of an Admiralty Prize Court where an Admiralty judge decided whether the boat and its cargo were lawful prizes. The Old Court House in St Aubin is generally thought to be the venue for this court. Later on commissions were issued to vessels authorising their owners to attack and plunder the King's enemies during wartime. A phrase typical of letters of marque was "to set forth in a warlike manner . . . with force of arms to apprehend, seize and take the ships, vessels and goods belonging to France and our other enemies . . . " Any prize was sold and the profit was divided amongst the State, the shipowners and the crew. By the end of the eighteenth century this was usually 20% to the Crown and the rest was divided between the shipowners who received two thirds (53%) and the crew who received the rest (27%). Each of the crew members received a predetermined number of shares in the prize money depending on their role and their position in the ship. Good captains were often part owners of ships as well. The return of a privateer from a successful voyage was greeted by much excitement with the crowds flocking to the shore to get all the news and to gossip. Bells were rung, drums were beaten flags were flown and guns fired as salutes. In 1779 the States even tried to prevent these tumultuous receptions by forbidding them. They must have failed because in 1793 the firing of cannon on the arrival or departure of a privateer was made punishable by a fine of 100 livres.

Once legalised, Jersey shipowners were quick to take up the chance and during the French wars 1692 - 1697 there were eight Jersey vessels engaged in privateering and between them captured they 46 prizes. It must have appeared as if they had been given a licence to print money. The oldest recorded Letter of Marque referring to Jersey was granted to Jean Mauger in 1692 for his 30-ton boat Jersey Sloop. However, it must be said that Guernsey with its deep-water harbour and its wealthier merchants had twenty-two privateering vessels at the same time. During the war of 1703 - 1711 the number of Jersey privateers had risen to 38 and between them they captured 151 prizes. In the same period the more numerous Guernsey privateers took 608 prizes. Guernsey was always able to produce more privateers than Jersey due to its deep-water harbour and its richer merchant class.

The average local privateering operation must have involved armed merchantmen with virtually double crews, which would be needed to man the "prize". However, some privateering was carried out by what we would consider ludicrously small boats. In 1759 Captain Peter Labey was granted a Letter of marque for a ship called the Fox; a nine ton row boat that could carry a lug sail which was armed with two swivel guns and crewed by twenty men. We have no records of the activities of the Fox but it must have been an interesting spectacle to watch it go into action. While many of the privateers were only lightly armed the crews were usually well equipped with firearms and because of their militia training were well versed in their use. Swivel guns were a popular form of armament because they were relatively light and could be hidden until needed thus providing an element of surprise.