This is something I collected for my monetary theory and policy course for the section on the evolution of money. These are regulations over a nearly 600 year time period (c. 681-1248) designed to overcome losses and transaction inefficiencies due to "sweating, debasing, clipping, and counterfeiting of coins":
From The Laws of the Visigoths: On Coinage, c. 681: Monetary regulations establishing a sound coinage formed a part of the program of the early kings of France, Anglo-Saxon England, Lombardy, and the Visigothic kingdoms for the enrichment of their territories. Sweating, debasing, clipping, and counterfeiting of coins prevalent throughout the Middle Ages indicate that the art of designing and striking coins was not highly developed.
Law of the Visigoths. King Eruigius:
V11.6.i. We do not forbid the torture of slaves by the lord or lady in person for cases of false money, so that the truth might be more easily arrived at by such torture; so that if the serf of another betray something, or say what is true, if his lord wishes it, he might be freed by his lord; and a reward should be given by the fisc to his lord. But if the lord be unwilling to free him, three gold uncias might be given by the fisc to the serf; if he be a free man he deserves six uncias of gold for revealing the truth.
V11.6.ii. Whoever shall have debased, clipped, or shaved the coinage should be arrested as soon as the judge learns of it, and, if he be a serf, his right hand should be cut off.
Vll.6.iii. Whoever takes gold for ornaments, debases it, or corrupts it with an alloy of bronze or silver or other more common metal, let him be held as a thief.
Vll.6.v. Let none dare to refuse a gold solidus of full weight, to whomsoever it belong, if it be not debased; nor require money of less weight for anything of his. Whoever shall do anything against this rule and refuse a gold solidus of full weight that is not false, or seek reward for changing it, shall be arrested by the judge, and compelled to pay three gold solidi to him whose money he refused. And one third of a solidus shall be kept by the judge.
Xll.3.xviii. One pound of gold is worth seventy-two solidi of gold. One uncia is worth six solidi. A stater of gold is worth three solidi. A drachma is worth twelve silver solid. A third of a gold solidus is worth five silver solidi. A seliqua is worth one and a third silver solidi.
Acts of the Synod of Pippin, c. 750.
C.5. And concerning money, we decree that in weighing there shall not be more than twenty-two solidi in one pound, and of these twenty-two solidi the moneyer shall receive one solidus and shall return the rest to the owner.
Capitulary of Frankfort on the Legality of Coinage, 794.
C.5. Know well our edict about the denarii, that in all places, in all states, and in all markets, the new denarii shall pass and be received by all. But if they have the nomisma of our name and are of pure silver and of full weight, and if any one refuse them in any place in negotiating a purchase or a sale, if he be a free man, he shall make amends to the king with fifteen solidi. But if he be servile, and if it be his olwn business, let him lose that business, or be stripped and publicly beaten in the presence of the people. However, if he do it by order of his master, then the master shall pay fifteen solidi, if it be proved against him.
Capitulary of Aix-la-Chapelle on the Value of Commodities, 797.
C.11. Be it noted how much the solidi of the Saxons ought to be worth; that is, a yearling ox of either sex, just as it is sent to the byre in autumn, one solidus; likewise in the spring, when it leaves the byre, one solidus; and from that time, as its age increases, so will it increase in price. Let those near to us give forty bushels of corn and twenty of rye for one solidus, but in the north thirty bushels of oats and fifteen of rye for one solidus. But for one solidus let those near to us give one and a half sigla of honey; but in the north let them give two sigla of honey for one solidus. Also they shall give as much good barley as rye for one solidus. Twelve denarii of silver shall make a solidus. And they are to estimate all other things according to that scale.
Capitulary of Diedenhofen Concerning False Money, 805.
C.18. Because in many places false money is made, contrary to justice and against our edicts, we command that money be made in no other place than our palace, except we command otherwise. But those denarii which are now current shall be accepted if they are of proper weight and of good metal.
Capitulary of Aix-la-Chapelle Concerning Adulterers of Money, 817.
C.19. Concerning false money, we have ordered that he who has been proved to have struck it shall have his hand cut off. And he who does not obey this, if he be free, shall pay sixty solidi; if he be serf, let him have sixty lashes.
Charles the Bald: Edict of Pistes, 864: The Council of Pistes was held in A.D. 864 and Charles the Bald there made full provision for the minting and acceptance of coinage, and regulated the punishment for counterfeiting. Prior to this edict at least nine places in France had the right of minting but these were reduced to three, the palace being one of them. This is one of the most complete and informative documents on Carolingian coinage.
C.8. It is ordered that denarii of all kinds, of proper weight and full content, just as is contained in the capitularies of our predecessors and royal progenitors, in the fourth book, the thirty-second capitulary, should not be rejected until Martinmas . . . nor should good denarii be rejected, but they should not be accepted unless properly and well weighed.
C.10. And from the time of the feast of St. Martin throughout our whole realm, no denarii, except those of our new mintage should be accepted. And from that day any one who produces another denarius for a business transaction should be deprived of it by the count or other official, just as is contained in the second book of capitularies, in the eighteenth chapter.
C.11. And on the denarius of our new money there should be on the one side our name in a circle and the monogram of our name in the center, and on the other side the name of the state and a cross in the center.
C.12. Following the custom of our predecessors, just as it is found in their capitularies, we decree that in no other place in all our kingdom shall money be made except in our palace, and in St. Josse and Rouen, which right in the past belonged to St. Josse, and in Rheims, Sens, Paris, Orleans, Chalon-sur-Saone, Melle, and Narbonne.
C.13. And those who have control of the money, with no desire for favor or gain, should select faithful coiners, as if they were seeking our favor and the grace of God. And the coiners should themselves take oaths that they will perform their office faithfully, as well as they know how. And they should not coin a denarius of mixed metal nor one of light weight, nor should they consent to such a thing. And, without any deception or evil disposition towards those whose silver they accept for purifying, they should cleanse the silver, and without practicing any deception in weighing it, they should change the purified silver into denarii. If it be reported that any one has acted contrary to his oath, he will be tried by the judgment of God; and if it be proved that he acted contrary to his oath he will lose his hand just as was decreed for false coiners in book four of the capitularies, chapter thirty-three, and as a sacrilegious person and despoiler of the poor he will be subjected to public penance by order of the bishop;---for he committed no greater fraud if he coined a denarius of mixed metal or of light weight than he would have done by taking the silver of the State, or of the Church, or of the poor, in purging and coining silver with evil intent. In those regions where trials are conducted according to Roman law, he will be tried in accordance with that law.
C.18. And if a false coiner from those places, in which we have decreed that money shall be made, stamps money secretly or offers a false denarius in a business transaction, so that he cannot be caught and punished; he will be seized by our minister, just as has been decreed, if he seeks refuge in our fisc, in any privileged place, or on the estate of any powerful person whatsoever.
C.19. In order that this provision for the non-rejection of good denarii, and concerning the making of false denarii, might be better observed, we wish that every overseer cause the markets of his district to be catalogued, that he report to us what markets there were in the time of our grandfather, and what new ones began in the time of our father, and what were established by his authority, and what markets began to come into existence in our own time, which of them remained in their ancient locations, and, if they had been changed, by whose authority they had been changed.
Æthelred Unrædy: The Laws of London, 978: For so long as Ethelred ruled over England the standard for London in the matter of coinage was the standard for all his dominions. His regulations about counterfeiting were applied to all towns under his jurisdiction. The reduction in the number of mints had as its object a better coinage system through more careful supervision. But Ethelred was a weak king and doubtless he did not enforce his laws.
C.5. Also they said that it did not appear to concern them that there was trade between coiners of false money and merchants who take good money to the coiners and buy from them so that they use impure and light coins, and then they furbish their goods and bargain and sell them to those who make coins secretly for money and they cut the name of other money on it and not of the impure. Wherefore it seems to all wise people that there should be three men of upright character. And if any of them be accused, be he English or foreigner, let him be put to the ordeal. And they decreed, that the coiners should lose their hand, and it should be placed above the money-smithy. And the coiners who work in the woods, or who make similar things anywhere, are guilty of their lives, unless the king wishes to have mercy on them.
C.6. And we command, in order that no one shall speak ill of pure money of correct weight, that it shall be struck only in whatever port it may be struck in my kingdom, upon pain of my displeasure.
C.7. And concerning merchants who bring false or chipped money to our port, we have said that they shall defend themselves if they are able; if they cannot, let them incur the penalty of their wer or of their life just as the king wishes; or, as we have said, let them prove themselves innocent in this ordeal that they knew there was nothing wrong with the money itself with which they carried on their business; and afterwards let him suffer the loss due to his carelessness, so that he exchange it with the decreed moneyers for money pure and of correct weight. And let the port-reeves who were cognizant of this offense be guilty of the same blame as the false moneyers, unless the king pardon them or they are able to exculpate themselves by the same cyrsth, or said ordeal.
C.8. And the king advises and commands his bishops, earls, and aldermen and all the reeves that they take care to see to those who make false money and transport it through the country, just as it has been ordered both among the Danes and English.
C.9. And let the moneyers be fewer than they were before; in every important port three, and in every other port let there be one moneyer; and let them have co-workers in their operations; let them make the money pure and of correct weight throughout the same witan as we have said before. And they who guard the ports shall take care upon pain of my displeasure that each coin conform to the standard at which my money is received and let each of these be stamped so that fifteen orae make one pound. And let all guard the money just as I have commanded and as we have chosen all to do.
Henry I of England: Monetary Regulations, 1108: Beginning with the reign of Henry I, who realized the great advantages of a sound and plentiful supply of money, and continuing with that of Henry II, English money reached a higher level of perfection which was maintained until the time of Henry III.
Flor. Wig. ii. 57. Henry, King of the English, established a lasting peace and decreed such a law that if any one were taken in theft or robbery, he was hanged. He also decreed that false and bad money should be amended, so that he who was caught passing bad denarii should not escape by redeeming himself but should lose his eyes and members. And since denarii were often picked out, bent, broken, and refused, he decreed that no denarius or obol, which he said were to be round, or even a quadrans, if it were whole, should be refused. By reason of this he did much good throughout the whole kingdom, because he did these things to relieve the land of its troubles forever.
Matthew of Paris: King Henry III’s Reformation of the Coinage, 1248: The practice of clipping and counterfeiting coins was prevalent in the reign of Henry III (A.D. I216-1272). Great hostility was aroused especially against foreign money-changers who accompanied the papal tax collectors and the merchants who attended the fairs. Matthew of Paris was well aware of the inconveniences arising from the process of improving the coinage.
About this time, the English coin was so intolerably debased by money-clippers and forgers, that neither natives nor foreigners could look upon it with other than angry eyes and disturbed feelings.
For it was clipped round almost to the inner part of the ring, and the border which bore the letters was either entirely destroyed or enormously defaced. Proclamation was therefore made by herald in the king's name in all cities, boroughs, and markets, that no penny should be taken which was not of legitimate weight and circumference, nor be received in any way, either in buying, selling, or exchange, and that all transgressors of this order would be punished...The French king also ordered all persons guilty of this crime who were found in his kingdom to be suspended on gibbets and exposed to the winds.... In the course of this year the people were so troubled by divers precepts of the king concerning the receiving of money, proclaimed by the voice of a herald throughout the cities of England, that they would rather a measure of corn had cost more than twenty shillings; for exchange was carried on but in few cities; and when they got there, they received a certain weight of new money for a certain weight of old, and were obliged to pay thirteen pence on every pound for the smith's work, or moneying, which was commonly called whitening. The form of this money differed from the old, insomuch that a double cross traversed the border where the letters were marked; but in other respects, namely as to weight, chief impression, and the lettered characters, it remained as before....