Dress Act

The Dress Act 1746 was part of the Act of Proscription which came into force on 1 August 1746 and made wearing "the Highland Dress" including tartan or a kilt illegal in Scotland as well as reiterating the Disarming Act. The Jacobite Risings between 1689 and 1746 found their most effective support amongst the Scottish clans, and this Act was part of a series of measures attempting to bring the warrior clans under government control. An exemption allowed the kilt to be worn in the army, continuing the tradition established by the Black Watch regiment.

The law was repealed in 1782. By that time kilts and tartans were no longer ordinary Highland wear, ended by enforcement of the law and by the circumstances of the Highland clearances, but within two years Highland aristocrats set up the Highland Society of Edinburgh and soon other clubs followed with aims including promoting "the general use of the ancient Highland dress". This would lead to the Highland pageant of the visit of King George IV to Scotland turning what had been seen as the uncivilised outfits of mountain thieves into national dress claimed by the whole of Scotland.

Abolition and Proscription of the Highland Dress 19 George II, Chap. 39, Sec. 17, 1746:

That from and after the first day of August, One thousand, seven hundred and forty-six, no man or boy within that part of Britain called Scotland, other than such as shall be employed as Officers and Soldiers in His Majesty's Forces, shall, on any pretext whatever, wear or put on the clothes commonly called Highland clothes (that is to say) the Plaid, Philabeg, or little Kilt, Trowse, Shoulder-belts, or any part whatever of what peculiarly belongs to the Highland Garb; and that no tartan or party-coloured plaid of stuff shall be used for Great Coats or upper coats, and if any such person shall presume after the said first day of August, to wear or put on the aforesaid garment or any part of them, every such person so offending ... For the first offence,shall be liable to be imprisoned for 6 months, and on the second offence, to be transported to any of His Majesty's plantations beyond the seas, there to remain for the space of seven years.

...
Wikipedia