Udal law is a near-defunct Norse derived legal system, which was formerly found in the Shetland islands and Orkney. Scottish Courts have intermittently acknowledged the supremacy of Udal law in property cases up to the present day. Major differences from Scots (and English) Law include shore ownership rights, important for pipelines and cables. Currently, Scots law generally holds sway in Shetland and Orkney, along with European law.
External links
Historical look at Udal Law. (http://www.charles-tait.co.uk/guide/udal_law.html)
Udal Law campaign group. (http://www.udallaw.com/)
Article including several case references. (http://www.orcadian.co.uk/archive/udallaw.htm)
Article on Udal Law and coastline ownership. (http://www.dundee.ac.uk/geography/s008.pdf)
On reflection, however, I feel that udallaw might have a wider relevance to the islands.
Their centuries-old right to do so is, I believe, founded in udallaw for it does not necessarily exist elsewhere in the law of Scotland and may exist no longer if the current 'right-to-roam' bill passes through the Scottish Parliament.
That all-embracing nature of udallaw was declared by a single, much-respected judge (Lord Lee) in 1890 in a case (Bruce v Smith) which related to Shetland (but would have equal application to Orkney) as follows:
Scots law (or Scottish law) is the law of Scotland.
By 1560 the Reformation removed Papal authority and Canon Law jurisdiction was taken over by the Commissary Courts, whose jurisdiction, along with that of the Scottish Court of Exchequer was subsumed into that of the Court of Session in the 19th century.
It is worth noting that Feudal law has never existed in the Islands of Orkney and Shetland, which rather use a system called UdalLaw, owing to their historic ties to Norway.