[4] Although paper money had firmly established itself in practice by the mid-18th century, its legal status was indeterminate without a body of case law to rely on.
[5] On 30 July 1748, an Edinburgh lawyer named Hew Crawfurd mailed two £20 notes to the merchant William Lang in Glasgow, but the letter was lost.
Prior to sending them, Crawfurd had meticulously signed his name on the banknotes and recorded their serial numbers, so he notified the Bank of Scotland and advertised his predicament in several newspapers.
[6] Both banks were alarmed by his action, as an adverse finding would subject banknotes to infirmities of title like any other property, which would threaten the idea of paper money as a common circulating currency.
[9] In a unanimous decision, the judges decided "that money is not subject to any vitium reale; and that it cannot be vindicated from the bona fide possessor, however clear the proof [of] the theft may be"; thus, "Mr Crawfurd had no claim to the note in question".
[12] American courts have developed a similar principle, on the basis of facilitating practical commerce by obviating the need to verify the provenance of money.