The 62nd Rule was a Romulan Star Navy D'deridex-class warbird that was illegally sold to the Ferengi Alliance before or during the year 2366. She was destroyed by another Romulan warbird while attempting to mediate the sale of a fragment of a Borg cube to the USS Enterprise in 2366. (ST novel: Federation)
In 2366, The 62nd Rule decloaked in front of the Enterprise as the latter was transferring Ambassador Sarek to the USS Merrimack. Data ordered the ship to red alert the moment he detected the cloaking device deactivating, but the crew were astonished to see Ferengi writing on the side of the D'deridex-class rather than Romulan. DaiMon Pol claimed to have purchased the ship, and asked to trade. After some negotiations Pol showed them an image of a fragment of a Borg vessel.
Captain Jean-Luc Picard and crew observed that the Ferengi were having difficulty operating the vessel (they had suffered a power failure after decloaking) and that Pol seemed to be in a hurry to make the sale, and inferred that the Rule had been stolen. After withdrawing to the Enterprise's observation lounge to discuss negotiating strategy, they alerted Admiral J.P. Hanson at Starbase 324 over subspace radio, then requested to beam across and examine the artifact in person. Instead, Pol gave them coordinates three light-years distant in deep space and told them to follow him.
When the Rule and Enterprise arrived, a second D'deridex-class, IRW Tears of Algeron, decloaked with her weapons and shields inactive. Commander Tarl hailed them and explained she had hired Pol to act as middleman, giving them the Rule as half payment (her own warbird was the other half). She offered the Borg artifact to Picard in exchange for a ship and colony supplies for her and her crew, along with a promise that the Federation would share anything they learned from the artifact with the Romulan Star Empire.
After Picard sent an away team to examine the artifact aboard Tarl's warbird, they agreed to the Romulan's terms and sent the shuttles Gould and Cochrane to bring the artifact across with tractor beams. At that moment a third D'deridex-class under the command of Traklamek suddenly decloaked behind the Rule and opened fire. The Ferengi still had only limited control over their systems and the Rule was obliterated in seconds. (ST novel: Federation)
The ship's name is presumably derived from the 62nd Rule of Acquisition, "The riskier the road, the greater the profit."