One take I have read on the causes of the Troubles in Northern Ireland was that there were a number of anti-Catholic practices, laws, and policies. What was the origin of this? Is it the old anti-Catholic laws and mistrusts from Protestant Britain (such as anti-Catholic voting laws), or something specific to Northern Irish politicians, or is there evidence to support this? Below are some examples.
(SOURCE) See also: Timeline of the Northern Ireland Troubles and peace process There is little agreement on the exact date of the start of the Troubles. Different writers have suggested different dates. These include the formation of the modern Ulster Volunteer Force in 1966,[60] the civil rights march in Derry on 5 October 1968, the beginning of the 'Battle of the Bogside' on 12 August 1969 or the deployment of British troops on 14 August 1969.[52]
Civil rights campaign and unionist backlash Main article: Northern Ireland civil rights movement(https://en.wikipedia.org/wiki/The_Troubles#Civil_rights_campaign_and_unionist_backlash)
In the mid-1960s, a non-violent civil rights campaign began in Northern Ireland. It comprised groups such as the Northern Ireland Civil Rights Association (NICRA), the Campaign for Social Justice (CSJ), the Derry Citizens' Action Committee (DCAC) and People's Democracy,[61] whose stated goals were:
*an end to job discrimination – it showed evidence that Catholics/nationalists were less likely to be given certain jobs, especially government jobs
*an end to discrimination in housing allocation – it showed evidence that unionist-controlled local councils allocated housing to Protestants ahead of Catholics/nationalists
*one man, one vote – in Northern Ireland, only householders could vote in local elections, while in the rest of the United Kingdom all adults could vote
*an end to gerrymandering of electoral boundaries – this meant that nationalists had less voting power than unionists, even where nationalists were a majority
*reform of the police force (Royal Ulster Constabulary) – it was over 90% Protestant and criticized for sectarianism and police brutality
*repeal of the Special Powers Act – this allowed police to search without a warrant, arrest and imprison people without charge or trial, ban any assemblies or parades, and ban any publications; the Act was used almost exclusively against nationalists
A while back I wrote about the origins of the Troubles— I am linking my previous answer here in case it's useful to you. I would actually write a wholly updated version of that post with some better historical context but alas I am traveling and do not have my bookshelf at hand! (Mods, hope this is ok to self-reference!)
That said I will point out a few things:
Is it the old anti-Catholic laws and mistrusts from Protestant Britain (such as anti-Catholic voting laws), or something specific to Northern Irish politicians, or is there evidence to support this?
The key thing about the Troubles is that they're not a battle between Britain and Ireland about the status of Northern Ireland, or between Northern Ireland and Britain about the status of Northern Ireland. They were a battle between two factions within Northern Ireland about where Northern Ireland should go: the Catholic nationalists angling for a united Ireland, and Protestant unionists firmly holding onto their British identity. Do note that lines between Catholic/nationalist and Protestant/unionist aren't quite set in stone and there is slippage between them.
Britain controlled Ireland since the 1800s, and there has always been a strong Protestant tradition in the north of Ireland— specifically the counties of Antrim, Armagh, Derry, and Down. These counties were the most industrialized part of Ireland and therefore had the most to gain from closer association with Britain; they also associated themselves with Britain and Britishness. Even today in these counties the Union Jacks fly high. This Protestant unionist faction bitterly opposed Irish nationalist attempts to secure a devolved parliament for Ireland, and for many years, their obstruction efforts were successful.
Right after World War I, however, nationalists in the southern part of Ireland— what is today the Republic of Ireland— fought for their independence from Britain in a bloody guerrilla war. In response, Britain partitioned Ireland in two: a government for southern Ireland, and a devolved government for the 4 Protestant counties and 2 Catholic ones, Fermanagh and Tyrone, which now make up Northern Ireland. (Because 4 counties was too small for a gov't, Fermanagh and Tyrone were added. The other 3 counties of Ulster were excluded because it would swing the majority away from the unionists. From its very founding, NI was designed to give unionists maximum power.) Southern Ireland became the Republic, Northern Ireland got the exact devolved parliament they never wanted. Irony!
This devolved parliament was controlled by unionists and often hard-line ones at that. It is actually this devolved parliament that passed the Special Powers Act in 1922, as a response to the violence and upheaval of partition— and then kept it on the books for decades, and justified it (along with the various other exclusionary policies you note) by stoking fears about violent nationalists who would incite disorder and reunite Ireland by any means necessary. Moreover, excluding and targeting Catholics allowed Protestants to maintain their control of not only the government but also of the region's major industries, ship-building and linen making. The irony is that Catholics pushed out of the trades usually entered the professions, and this led to the creation of a Catholic middle class that challenged and critiqued the laws that led to their exclusion. So the anti-Catholic policies are not holdovers from British rule so much as they are policies of Protestant Northern Ireland.
Sources & further reading:
RF Foster, Ireland 1600-1972
Diarmaid Ferriter, The Transformation of Northern Ireland 1900-2000
Peter Rose, How the Troubles Came to Northern Ireland
edited for style & clarity