The True Meaning of Friends: ‘Cairde’ and Cross-Border Law in Early Ireland

Ireland is an active participant in multilateral institutions, such as the United Nations, established to uphold international law, as well as having contributed to a number of (often dangerous) international peacekeeping missions. Ireland also adheres to various multinational frameworks for handling cross-border legal proceedings. This basic notion of vindicating shared legal interests across borders can, however, be traced much further back into the mists of history.

In this article I survey one way (the cairde) in which cross-border legal interests could be secured in the highly fragmented political structure of early Ireland. In Modern Irish, cairde is usually translated as ‘friends’. But the more literal translation of cairde is ‘kinship’ and the term was originally used to denote a type of inter-territorial treaty under the Brehon Laws.

Proto States’ in Early Ireland

It is sometimes suggested that early Ireland was ‘stateless’ and, to a degree, that is true. There was no centralised nation state in the modern sense. But an array of ‘petty kingdoms’ (túath) were scattered across the island, slotting into a broader patchwork of over-kingdoms, themselves funneling into loose provincial kingdoms. To give a sense of the political congestion, the number of kings/chieftains at any time between the 5th and 12th centuries is estimated to have been at least 150 [1]. Each túath was a jurisdiction in its own right, though sharing a common legal culture with the others.

While lacking a centralised state, the stability of each túath at least partly rested on the effective control of its inhabitants’, not least to reduce the potential for violence. The Brehon Laws suggest that social order in early Ireland was maintained, in essence, through a complex system of kin (fine) group oversight and hierarchical, honour-based legal relationships [2]. This setup was underwritten by the nobles and learned classes, such as jurists, poets and clerics.

The noble and learned classes in a túath therefore performed types of ‘public officer’ roles in service of social stability. When considered together, they resembled an embryonic form of government. It has thus been argued that early Irish túatha can be perceived as ‘proto-states’ [3]. By extension, a distinct body of law also emerged to govern cross-border legal disputes between people located in these different proto-states. Key aspects of this are explored in the next section.

Image 1: Irish Political Landscape c. 800 A.D. Image Credit: Mike Christie, ‘Ireland, early peoples and politics’, Wikimedia Commons, redrawn from a map in Sean Duffy, Atlas of Irish History (Gill & MacMillan, 2012) (link)

Cairde: Crossing the Border (Law)

A number of Brehon Law sources address the topic of cairde, including for example Bretha Cairdi (‘Judgments concerning cairde‘). These agreements could take more or less limited forms [4]. A ‘full’ cairde could arise when neighbouring kings met at the border and swore that compensation payments should be made across their boundaries for certain serious offences. It may often have been the case that cairde agreements were struck following the commission of an offence, after which the victim’s king would lead troops to the border and seek a cairde on pain of military action [5]. A cairde might also have been publicly endorsed at an óenach (fair/popular assembly) in each kingdom [6].

Once agreed, a cairde typically contained a ‘suretyship’ (guarantor) mechanism, known as an aitire cairde (translated ‘betweenship’) [7]. This was a type of ‘hostage surety’ in the form of a person/s who could, if necessary, be taken back over the frontier as security for payment. Bretha Cairdi confirms: Co ndentar cairde ríg? toingthi in ríg ’ænur híc 7 fuaslucud n-aitire; ní h-ed tongar and na foruastar acht cid foruastar, a icc : ‘How is a king’s cairde made? The king on his own swears that hostage-sureties will be paid for and released. It is not that it is sworn there that will be no transgression, but that if there is, it will be paid for’ [8].

An aitire cairde may typically have been a noble lord or other high-ranking individual, sometimes possibly a tánaise (‘tanist’), i.e. the second in line or deputy to the king or another high officer [9]. The seniority of an aitire upped the stakes of breaching a cairde.

It also seems that ‘enforcing officers’ (muiredaig) were designated for each kin group in both kingdoms. An enforcing officer was typically of high social standing too – likely a senior ranking noble lord, an aire tuísea (‘lord of leadership’) or an aire forgill (‘lord of superior testimony’) [10]. In performing this function, lords acted in the interests both of their kin and their ‘clients’, i.e. other people from the farming classes contracted to supply food and/or personal service.

The standard procedure following commission of an ‘out of túath‘ offence was for a muiredach and a retinue from the victim’s kingdom to cross the border and present themselves at the dwelling of the king of the offender’s kingdom. From there, the aitire cairde for the offender was summoned and informed of the offence. The aitire cairde would accompany the muiredach to the offender or the offender’s kin and demand compensation for the offence [11]. Where liability was contested, the offender’s kin may have sought to refer the matter to a brithem (judge) for arbitration [12]. If made aware, the offender’s head of kin (cenn fine or aire coisring) may also have pressurised them to settle the matter. Failing all of this, the aitire cairde of the offender would be ushered across the border by the muiredach in pledge for payment of the debt [13].

A period of time would then elapse and, if the debt had still not been paid, the aitire cairde was either forfeited to the victim’s kingdom, presumably becoming a slave of the muiredach, or could regain their freedom by paying a ransom plus the outstanding debt [14]. Given the usually high status of an aitire cairde, they often probably had little difficulty ransoming themselves out of hostageship. The freed aitire cairde would then return to their own kingdom and lodge a claim there against the original offender for the ransom fee, plus at least twice the original debt [15]. Alternatively, the offender’s kin may have been forced to become ‘clients’ of the aitire [16], thereby required to enter a food producing contract.

In a case of homicide, if compensation was not secured from an offender or their aitire cairde (probably within a one month period) then things could take a legitimately violent turn. Another ‘officer’ of the tuath, a so-called ‘noble of vengeance’ or ‘lord of slaughter’ (aire échta) and their supporting band, could be dispatched from the victim’s kin (fine) on a vendetta over the border to seek dígal (‘redress’ or ‘vengeance’) [17]. The law text Críth Gablach (‘Branched Purchase’) confirms the aire échta as:

…Arindí as n-aire cóicir fácabar fri dénum n-échta i cairddiu co cenn mís do dígail enechruccai tuaithe dia ndéntar dédenguin duini: ‘…the leader of a ‘group of five’ [i.e., of a kin-group] which is excluded from committing slaughter under a treaty until the end of a month, to avenge the dishonouring of a kingdom from which a person has recently been slain’ [18].

Image 2: Reconstruction of a roundhouse, Craggaunowen, County Clare. An aitire cairde and a muiredach might present themselves at the doorway of a similar-looking dwelling when seeking compensation for a cross-border offence in early Ireland. More concerning would be a late night visit from an aire échta (Image Credit: Wikimedia Commons, CC BY-SA 2.0)

Early Economic Zones?

There are hints from the broader literature that common economic and legal zones may also have been established between kingdoms subject to cairde agreements. For instance, the eighth century text Frithḟolad Caisil fri túatha Muman, dealing with various obligations between the king of Cashel and a number of Munster kingdoms, includes this passing reference:

Frithfolaidh Caisil. uaidib-seom dino, comgíall, ocus comurradhas, ocus comfonaidm, ocus comchairde, fria ferand ó chach diaraile: ‘The counter-obligations of Cashel: from them [the Uí Fhidgenti, Raithlend, and Íarlúachar] therefore, acknowledgement in joint hostageship, joint ordinary law, joint contracting, and joint cairde throughout their lands from each to the other’ [19].

This implies these kingdoms shared the same ‘common customary law’ (urradhas) and facilitated cross-border economic contracts between their peoples, parallel to having cairde agreements in place [20] – perhaps representing the early stirrings of ‘single economic communities’.

Some concluding thoughts

It can be tempting to think of international law and multilateral cooperation as a quintessential activity (responsibility even) of modern ‘nation states’. And it can often be assumed that frameworks underpinning cross-border cooperation in dealing with criminal offences and civil claims are the scaffolding of a uniquely complex modern legal environment.

Basic tendencies to legally (and sometimes economically) cooperate across political boundaries in pursuit of mutually beneficial social stability can, though, be traced much further back in time. The precise mechanisms of this cooperation are, of course (and thankfully), substantially different today. However some of the modern artefacts of cross-border legal cooperation appear to echo those deployed in ancient legal systems, such as the Brehon Laws, as applied by early Irish ‘proto-states’ – for instance: the notion of public officers cooperating across frontiers; mutual assistance on both sides of a border; and ensuring political and public endorsements of treaties entered into etc. It is also clear that the true meaning of friendship was both legal and political in early Ireland.

This article may be cited as J. Biggins, ‘The True Meaning of Friends: “Cairde” and Cross-Border Law in Early Ireland‘, The Brehon Lawyer (September 2021)

Sources used in this article

Andrew Ó Donnghaile, ‘An Overview of Inter-territorial Law in Early Ireland’ (2019) 30 Peritia 197

Fergus Kelly, A Guide to Early Irish Law (Dublin Institute for Advanced Studies, 2009)

Jaqueline Bemmer, ‘The Early Irish Hostage Surety and Inter-territorial Alliances’ (2016) 89 Historical Research 191

Nerys Patterson, Cattle Lords and Clansmen: The Social Structure of Early Ireland (University of Notre Dame, 2012)

Robin Chapman Stacey, The Road to Judgment: From Custom to Court in Medieval Ireland and Wales (University of Pennsylvania, 1994)


[1] Kelly, pp. 3-4

[2] Patterson

[3] Patterson, p. 329

[4] Bemmer, p. 197

[5] Ó Donnghaile, p. 201

[6] Bemmer, p. 193

[7] Bemmer, p. 194

[8] Ó Donnghaile, pp. 200-201

[9] Chapman Stacey, p. 92

[10] Ó Donnghaile, p. 205; Patterson, p. 353

[11] Ó Donnghaile, p. 206

[12] Ó Donnghaile, p. 203

[13] Chapman Stacey, pp. 90-91

[14] Chapman Stacey, p. 91

[15] Chapman Stacey, p. 91

[16] Bemmer, p. 207

[17] Patterson, p. 350

[18] Bemmer, pp. 200-201

[19] Ó Donnghaile, p. 209

[20] Ó Donnghaile, p. 209