The feigning of folly could be profitable and in 15th century Scotland it appears there was enough of it going on to prompt a law prohibiting it. This and similar constraints were repeated in the parliamentary records for another 150 years or so; I have found such references from this first one, in 1450, to 1593. It was:
… ordainit that sheriffs, baylyiss, and officials inquer at ilk court gif thair be ony that maks them foolis that are nocht; and gif ony sic be fundyn, that thai be put in the king’s warde, or in his yrnis, for thair trespass, as lang as thai haf ony gudes of thair awin to leve upon; and fra thai haf nocht to leve upon, that thair eris be naylt to the trone, or to ane uther tre, and cuttit of, and bannysit the cuntre; and gif thairafter thai be fundyn again, that thai be hangyt.
The online Records of the Parliaments of Scotland to 1707 gives a version easier to read but still wince-making when you come to the punishments for those who act as fools without being so. Interestingly, the modernised version below mentions ‘fools that are not bards’, apparently recognising that an authentic court fool might have functions overlapping with bards.
Item, it is ordained for the putting away of sorners, overliers, masterful beggars with hors, hounds and other goods, that all officers, both sheriffs, barons, aldermen and bailies, both within and outwith burghs, take inquiry at each court that they hold of the foresaid things, and, if any such are found, that their horses, hounds and other goods be escheat to the king, and his person put in the king’s ward until the king has said his will to them. And also that the said sheriff, bailies and officers inquire at each court whether there are any that make themselves fools that are not bards, or such like runners about. And if any such be found, that they be put in the kings ward, or in his irons, for their trespass, as long as they have any goods to live upon. And from the time that they have nothing to live upon, then their ears shall are to be nailed to the tron, or to another tree, and their ears shall be cut off and [they shall be] banished from the country. And if thereafter they are found again, that they be hanged.
Further references to feigned fools include the parliamentary record for 6 March 1458:
Item, the lords think it profitable that in all justice ayres the king’s justice cause inquisition to be taken of sorners, bards, masterful beggars and fained fools and either banish them from the country or send them to the king’s prison.
And again on 12 September 1593, where there is also a mention of those who disguise themselves in ‘fool’s costume’.
The dire punishments meted out to feigners of folly didn’t seem to stamp out the practice as the litany of torture is repeated in the parliamentary records of 5 March 1575.
For the other side of this legal coin, see also ‘Begging a fool’.
Sources: Act for the away-putting of Feynet Fools was passed on 19 January 1449 (1450), see Thomas Thomson, Acts of Parliament of Scotland, vol. 1, quoted in J.B. Pratt, The Life and Death of Jamie Fleeman, the Laird of Udny’s Fool, 3rd edn (Aberdeen: Smith, 1912), pp. 10-11; other extracts from the parliamentary records are found in the online searchable Records of the Parliaments of Scotland to 1707.