What makes money special, the lawyer's edition (with a guest appearance by bitcoin)

Juan Galt recently introduced me to one of bitcoin’s biggest problems. Bitcoin is not money, at least not according to the law.

Economists like to say that money is unique because it is a medium of exchange, store of value, and unit of account. Lawyers and judges have a different story to tell about money’s uniqueness. Unlike goods, money can’t be ‘followed.’ When a good is exchanged, its entire history goes with it. This history may be checkered. Say that a car has been stolen at some point in its past and then sold, and the police discover this fact. The current owner—though having purchased the car innocently—is required to return it to its rightful owner. The law ‘follows’ goods.

With money things are different. Each time a monetary instrument is transferred, its history is wiped clean. As long as the recipient accepts the money in good faith, the original owner of stolen dollars cannot make a claim for those dollars.

This peculiar legal treatment of money, dubbed money’s liability limitation by Steve Randy Waldman, ensures fungibility. When all members of a population can be perfectly substituted for each other, than we say that they are fungible. If each monetary unit’s unique history becomes a datum that merchants must take into account before selling a good, then fungibility no longer prevails. One unit may be worth more than another because its history is more pristine.

Fungibility is important because it promotes the smooth functioning of a monetary system. If merchants have to analyze each piece of money they are offered to ascertain its legitimacy, long lineups will develop. Exchange grinds to a halt.

So why not extend the status enjoyed by current forms of money to bitcoin? What follows is a quick tour through the history of how jurists have rationalized the legal treatment of other forms of money, including coins, banknotes, and bills of exchange. This should provide us with enough grist to analyze bitcoin’s current legal status.


Let’s start with coins. The basic principle of nemo dat quod non habet governs property; no one can give away that which they do not have. According to early common law jurists, coins were exempt from nemo dat because they couldn’t be followed. The inability to follow coins arose from the fact that they were homogeneous. In the words of the jurists of the day, ‘money has no earmark.’ Whereas one pig could be differentiated from another thanks to the practice of earmarking—cutting out a distinct piece from a pig’s ear—coins could not be earmarked, and therefore could not be differentiated.

Thus there was no way for a victim to lay claim to lost or stolen coins. With no way to prove that the coins in the accused’s pockets had not already been there, mixed coins could not be sufficiently distinguished to establish title. James Fox, for instance, cites a 1614 case in which a gambler, Warde, “thrusts” his coins into the stack of another gambler, Aeyre, perhaps hoping to get a tell from of his opponent. Aeyre refuses to give the coins back. The judge upholds Aeyre’s rights to the entire stash since money has no earmark, and therefore nemo dat does not apply. Once mixed, who ever possesses the pile of coins has the best title.

Interestingly, the only way to preserve ownership of coins in the medieval era was to keep them in a bag. Since they could now be identified by the distinctiveness of their container, like any other good they were subject to nemo dat. Had Aeyre’s coins been bagged, he could have easily mixed them with Warde’s without losing title to them.

The fact that coins had no earmark meant that each piece’s distinct past was irrelevant. While this was awkward for poor Aeyre, society was made better off by this decision. Coins became much more fungible than they otherwise would have been, and this would have dramatically promoted their use in trade, greasing the wheels of commerce in general.

Let’s move on to paper credit, namely bills of exchange and banknotes. While bills of exchange developed in the 12th or 13th century, the first notes would not have appeared in England until the 17th century. Though English common law was useful for land disputes, it had not yet developed the expertise to deal with commercial disputes. Indeed, common lawyers’ expertise with commercial matters was so limited that Josiah Child, an English trader, complained that he could only make his lawyers understand “one half of our case, we being amongst them as in a Foreign Country.”

Rather than resorting to common law, problems arising from the usage of negotiable instruments like bills were governed by lex mercatoria, or merchant’s law, a private form of commercial law or custom that had been developed by European merchants over the preceding centuries. Market courts, operated by the merchants themselves, guaranteed a decision the day after a complaint, a necessity given the mobile nature of commercial life.

According to Lowry, the close-knitted nature of the merchant class began to unravel by the end of the seventeenth century, making merchant law less enforceable. As commercial cases were increasingly brought to common law courts, jurists had to decide how to treat these new financial innovations.

Lex mercatoria had always accepted the principle that, as in the case of coins, bills of exchange could not be followed. Since those who accepted bills of exchange didn’t have worry about whether they had been stolen or not, this would have made trade in bills of exchange extremely fluid. However, the stance taken by lex mercatoria was an anathema to common law logic. Unlike coins, which couldn’t be followed due to their lack of earmark, both bills of exchange and banknotes did have earmarks. Whereas coins were issued in uniform denominations, bills of exchange were usually made out in non-standard ones, say $101.50, making for easy identification. Bills were also signed by a unique debtor and a range of consignees. As for banknotes, these had serial numbers on them. Without the homogeneity of coins, there seemed to be no way to save the these relatively new financial instruments from the harsh strictures of common law nemo dat. Goods they were to be, not money.

It was Lord Mansfield, an English jurist, who took on the task of incorporating lex mercatoria into English common law (Adam Back notes a similar case in Scotland). Take Miller v Race, Mansfield’s definitive ruling on banknotes in 1758. The note in question had been issued by the Bank of England “to William Finney or bearer on demand” and subsequently mailed to a third party by Finney. Along the way it was stolen and used to buy room and board at an inn, the innkeeper Miller innocently accepting the note. Finney, upon learning of the robbery, asked Race, an employee at the Bank of England, to stop payment of the note, upon which Miller the innkeeper sued Race. If the bill was treated as a regular good, then Finney would have prevailed. However, Mansfield ruled that despite the note having been stolen, Miller had the best title and was allowed to keep it.

In justifying his ruling, Mansfield dismissed as “quaint” the old earmark principle for not following money. Instead, he appealed to the common mercantile practice of the day. Banknotes, wrote Mansfield, are:

not goods, nor securities, nor documents for debts, nor are so esteemed; but are treated as money, as cash, in the ordinary course and transactions of business, by the general consent of mankind, which gives them the credit and currency of money to all intents and purposes. The are as much money as guineas themselves are, or any other current coins that is used in common payment as money or cash. 

The true reason that money cannot be followed, said Mansfield, is upon “the currency of it; it can not be recovered after it has passed in currency.” Thus had Finney sued the robber before he had spent the stolen note, he would have succeeded in claiming title since the note had not yet passed into currency. But once Miller accepted it, the note was “in currency” and thus out of nemo dat’s reach. In subsequent rulings, Mansfield extended this same protection to bills of exchange, cheques, bonds, and exchequer bills. Any contrary decision would “incommode” trade and commerce, wrote Mansfield. Thus the customs of merchants were transcribed into common law.

So both lex mercatoria and the common law tradition that superseded it accepted the principle that in order to protect commerce, highly liquid instruments should not be subject to nemo dat.  Given this precedent, why not extend this same broad amnesty to modern monetary innovations like bitcoin, Fedcoin, or other digital bearer tokens?

One reason could be that bitcoin hasn’t proven itself yet. Whereas bills of exchange and banknotes had been widely accepted for decades, even centuries prior to Mansfield’s ruling, bitcoin is less than a decade old. It fails the my-grandmother-uses-it-test or, in Mansfield’s words, lacks the “general consent of mankind.” People seem more intent on hoarding the stuff than trading it around in the “ordinary course of business.” Unfortunately there is a chicken-and-egg dynamic at play here; how can bitcoin gain enough consent to be granted amnesty by the law if it needs amnesty to gain consent in the first place?

Lacking common law amnesty from nemo dat, an alternative would be to modify bitcoin so that it is completely anonymous. Although it is true that the real world identity of a bitcoin owner remains unknown, the blockchain itself is a publicly-distributed ledger that reveals the history of every single bitcoin. Removing the ability to see the ledger’s history would restore true anonymity. In the same way that coins were originally exempt from nemo dat because they were physically impossible to follow, modern law would not be able to trace any given bitcoin because there would be no means to do so. Anonymity in turn guarantees fungibility, without which mass market adoption might never happen. My understanding is that extensions such as Zerocoin or Zerocash would be able to achieve this sort of true anonymity.

The third route is to roll with the punches and accept non-fungibility. If merchants must search each bitcoin’s past, they will innovate solutions to cope. One innovation would be to set up a system for grading bitcoin so as to save on transaction time. Tokens that pass a test of authenticity would be accepted at par whereas low grade bitcoin, that which has a soiled history, would pass at a large discount to pure bitcoin. I believe that a few bitcoin grading services have emerged, including Mint Exchange, which sells freshly-mined bitcoin (which are unburdened by a history) at a premium to regular bitcoin.

Let’s explore the third route a bit more. There is precedent for non-fungible monetary systems. During the so-called Wildcat banking era in the early to mid 1800s, U.S. privately-issued banknotes of the same denomination (say $1) were often  accepted at varying discounts to par. A $10 note from a the Bank of Talahassee might only be worth 98% that of a $10 note from the Bank of Fargo.

While banking regulations prevented note-issuing banks from establishing branches beyond state borders, nothing kept their notes from circulating outside of their home state. However, for notes to be settled in gold, they had to be returned to the issuing bank. Given the large distances involved and lack of transportation infrastructure, this could be an expensive process. To recoup this cost a merchant would typically accept local notes at par while applying discounts to non-local notes. The discount acted as a fee that covered the merchant’s transportation costs. And since each bank’s brand of notes involved different transportation costs, there were a bewildering number of discounts.

To solve the non-fungibility problem, a new profession emerged, that of a banknote analyst. In addition to providing merchants with information on how to spot counterfeit bank notes, an analyst would publish a weekly banknote reporter that advertised the market price of each banknote that circulated in a particular city, say Philadelphia. Gary Gorton provides a visual feel for what one looks like. Philadelphian merchants who subscribed would, upon being proffered a particular note by a customer, consult their reporter and apply the proper discount. I’ve explained in more depth how this process worked here and here.

While a Wildcat-era sorting mechanism for bitcoins would help merchants cope with the fungibility problem, any sort of grading process would also impose an extra set of costs on the bitcoin system, making it less competitive with banknotes and deposits. The lack of uniformity of U.S. banknotes was recognized to be enough of a problem that the 1864 National Banking Acts required all banks to accept notes at par (it would have been better to allow banks to establish branches across state lines, of course. See George Selgin here).

Uniformity would certainly be the most efficient solution for bitcoin, but lacking a central authority that can enforce par acceptance, bitcoin may have to endure a period of non-fungibility before the law deems the cryptocurrency popular enough to earn amnesty from nemo dat. That’s a low bar to set, but if bitcoin is as good as its proponents say, it should be a bar that can be limbo-ed.


S. Todd Lowry: “Lord Mansfield and the Law Merchant: Law and Economics in the Eighteenth Century” (1973) [link]
Benjamin Geva: “The Payment Order of Antiquity and the Middle Ages” (2011)
Kenneth Reid: “Banknotes and their Vindication in Eighteenth-Century Scotland” (2013) [link]
David Fox: “Banks v Whetston” in Landmark Cases in Property Law (2015)
Tim Swanson: Unable to dynamically match supply with demand (2015)
Nick Szabo: From Contracts to Money (2006)

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