Ewan MacColl sang The Laird o' Wariston in 1982 on his and Peggy Seeger's Blackthorne album Blood & Roses Volume 2. They noted:
"Jean Livingstone of Dunnipace and John Kincaid of Wariston, the two main protagonists in this prosaic domestic tragedy, were (according to contemporary accounts) married against their will at a very early age. Kincaid's consistent ill-treatment of his young wife eventually caused her to murder him. Janet Murdo, her nurse, and Robert Weir, a former servant in her father's house, helped her to carry out the deed.
" No attempt was made to cover up the crime and within three days of having committed it Jean Livingstone was tried, found guilty and condemned to death. She was beheaded at the Canongate in Edinburgh on 5 July 1600 and Janet Murdo was burned at the stake on the same day. Robert Weir fled but was apprehended four years later and was executed by having his body broken on a cartwheel by the coulter of a plough."
00000 From that information, I would think that Robert Weir's execution was outside of the law (like a lynching), but that Jean Livingston faced "capital punishment" after a trial.