On 6 March 2024, the Supreme Court, in judgments handed down by the Chief Justice, Hogan J and Murray J, has fundamentally changed the approach which the High Court should take in considering any application for an interlocutory injunction so as to restrain picketing and industrial action which is sanctioned or supported by a trade union.  It has done so by emphasising the constitutional foundation of the right of association and given effect to the clear meaning of section 19(2) of the Industrial Relations Act 1990.  


The facts of the case (HA O’Neil Limited v Unite the Union and others) are that the company is a mechanical engineering firm engaged in the construction industry. The union organises workers in the mechanical engineering industry, including employees of the company. In February 2023, the union, having balloted its members employed by the company, wrote to the company giving notice of the industrial action due to take place 10 days later. The industrial action involved targeted strikes taking place on a rolling basis at third party sites at which company employees were working. The company brought an application for an interlocutory injunction restraining the union and named employee defendants from picketing the third party sites and sought certain ancillary orders. The injunction was granted and the Supreme Court permitted a leapfrog appeal on the basis that the case raised important issues of law relating to the grant of injunctions in respect of industrial disputes, with particular reference to section 19(2) of the Industrial Relations Act 1990 and related matters. 

Before going into the Supreme Court decision in detail, it is worth first setting out what section 19(2) of the Industrial Relations Act 1990 provides: “Where a secret ballot has been held in accordance with the rules of a trade union as provided for in section 14, the outcome of which or, in the case of an aggregation of ballots, the outcome of the aggregated ballots, favours a strike or other industrial action and the trade union before engaging in the strike or other industrial action gives notice of not less than one week to the employer concerned of its intention to do so, a court shall not grant an injunction restraining the strike or other industrial action where the respondent establishes a fair case that he was acting in contemplation or furtherance of a trade dispute.” 

Tests to be applied

The Supreme Court noted that in order to secure an interlocutory injunction it will be necessary for it to be established that: 

  • section 19 does not bar the grant of an injunction, noting that this is for the union to establish;
  • that the statutory immunities and protections in sections 10 (actions in contemplation or furtherance of a trade dispute), 11 (peaceful picketing) and 12 (removal of liability for certain acts) of the 1990 Act do not apply in relation to the defendants, noting that this is for the employer to establish;
  • that section 13 (restriction of actions of tort against trade unions) does not apply in respect of the claim against the trade union, again noting that this is for the employer to establish; and 
  • that an interlocutory injunction should otherwise be granted by reference to the well-established criteria for the grant of an interlocutory injunction, again a matter for the employer to establish. 

“No strike” clauses 

The Supreme Court also held that the existence of a “no strike” clause in a collective agreement or in a Sectoral Regulation Order does not disapply section 19(2) and, accordingly, is not a basis upon which an injunction can be granted.  That is so because the Supreme Court concluded that section 19(2) is not confined to injunction applications based on the law of tort but extends also to injunction applications based on the law of contract.  The Supreme Court also held that the existence of a “no strike” clause does not prevent employees to whom it applies from participating in the required secret ballot, nor does such participation create circumstances in which it cannot be contended that there is a trade dispute.  

Approach of the Court 

The Supreme Court concluded that it was not correct for the courts to approach this area of law:  

“… on the basis that industrial action is presumptively wrongful and tortious, and that the 1906 and 1990 Acts should be viewed as providing islands of immunity which are exceptions to the general rule, and which must accordingly be strictly construed This, in my view, would be to ignore a clear objective of the legislation, the history against which it is to be understood, and indeed, the constitutional context in which it is to be read.  It is true that both of the 1906 and 1990 Acts are framed as providing immunities from actions, principally for tort, against unions and their members.  But it must be recognised that those torts were created by the Victorian common law in response to the activities of trade unions, which were regarded as criminal and tortious.” (Paragraph 57, O’Donnell CJ)

The Supreme Court’s approach was also grounded in the Constitution and in particular the right to form associations and unions.  The Court noted that: 

“The right to form unions would be of little benefit if the activities of the union and its members were to be regarded as presumptively unlawful.  Whereas the common law insisted on seeing employment as the exercise of the freedom of contract between an individual and his or her employer, and thus ignoring the inequality of bargaining power, the organisation of employees in a trade union offered the possibility of balancing the collective power of the employees and the economic power of their employer, allowing issues in relation to contract to be resolved by collective bargaining and disputes to be pursued, if necessary, by collective action… The 1990 Act should not, therefore, be read narrowly or restrictively, but should be read to give effect to the protection of unions and their members which the Acts were clearly intended to provide…If anything given the constitutional context just discussed, it would be appropriate to read the provisions of the Act generously to give full effect to the rights sought to be protected.” (Paragraph 59, O’Donnell CJ)

What the union must establish

The Supreme Court concluded that, with reference to section 19(2), an interlocutory injunction must not be granted if the trade union respondent establishes four things, namely that: 

  • a secret ballot has been held in accordance with the rules of the trade union as provided for in section 14 of the 1990 Act;
  • the outcome of the ballot favoured a strike or other industrial action;
  • not less than one week’s notice has been given to the employer concerned of the intention to engage in the strike; and 
  • the trade union respondent to the injunction application has established a fair case that they were acting in contemplation or furtherance of a trade dispute. That fair case must be established by the trade union respondent on the balance of probabilities.   

The Supreme Court made it clear that it is not the law that the prohibition on the granting of interlocutory injunctions, contained in section 19(2), can be disapplied if the plaintiff employer can establish a fair case to the contrary.   

On the facts of this particular case, there was no issue as to the holding of the ballot (it was not within the scope of the appeal); there was no question that the outcome of the ballot favoured of the taking of the industrial action; and there was no question that notice of not less than one week was provided.  The union succeeded in establishing a fair case that the industrial action was in contemplation or furtherance of a trade dispute.   

The Supreme Court concluded:

Where it was once easy to obtain an interlocutory injunction, it should now be extremely difficult to, even where an employer may have an arguable, indeed strong case, that the industrial action is unlawful.  The uncertainty of the application of the law to the facts of a case which was a factor weighing strongly in favour of the grant of an injunction, has now been neutralised in the hands of the employer, and instead becomes a factor which weighs strongly against the granting of an injunction.  For example, if it is only arguable that this is not a trade dispute, it follows, as a matter of logic, that it is also, at least arguable, that it is.  If so, it must also follow that the respondent to the application can establish a fair case that he is acting in contemplation or furtherance of a trade dispute.  The uncertainty in relation to the legal argument, which hitherto had been capable of being exploited on behalf of a party seeking an interlocutory injunction, now leads to its refusal.” (Paragraph 64, O’Donnell CJ)

The usual injunction criteria 

Finally, and tellingly, the Supreme Court concluded that even if section 19(2) did not operate to prohibit the granting of interlocutory injunction, in this case an injunction should not have been granted even applying the normal criteria, namely arguable case and balance of convenience. Traditionally, in considering the balance of convenience, the courts have favoured the employer by reason of likely disruption of the employer’s business and the inadequacy of damages. The Supreme Court however, emphasised the importance to employees of being permitted to engage in industrial action and the loss that they would suffer by being wrongfully restrained.

It stated: “The ability to engage in lawful industrial action is an important right in civic, societal, legal and constitutional terms (and one which is much valued by employees and trade unionists). An important part of the value of any such right is that the individuals concerned choose when to exercise it.  It is not, for example, an answer to a person who seeks to exercise their right to free speech in public on a given occasion, to tell them that they cannot express their views now or here and to those they wish to address, but may be allowed to speak much later in a different place perhaps in private or at least to a different audience.  The loss of that opportunity to exercise a lawful entitlement when one chooses to do so is at the level of principle precisely the type of loss which cannot be compensated for by the award of monetary damages, or indeed, even assessed in monetary terms.  In the context of an industrial dispute there is the additional consideration that the postponement of an ability to engage in industrial action may empty that right, not just of theoretical, but also practical valueIn my view it was possible to resolve this case on the balance of convenience alone, and by concluding, at a minimum, that it had not been demonstrated that the balance of convenience favoured the grant of the injunction.” (Paragraph 72, O’Donnell CJ)


It would appear that two possible grounds remain on which an injunction might be granted to restrain peaceful picketing, even where the conditions set out in section 19(2) might be satisfied. They are as follows: 

  • in circumstances where it has been contended that there has been an irregularity in the conduct of the ballot and the trade union respondent fails to satisfy the court with reference to same; and
  • in circumstances where there is a registered employment agreement, noting that section 8(3)(d) of the Industrial Relations Act 2015 gives apparent statutory effect to the non-application of section 19(2) by requiring that an agreement, if it is to be registered, must provide that “… if a trade dispute occurs between workers to whom the agreement relates and their employers, industrial action or a lock-out should not take place until the dispute has been submitted for settlement by negotiation in a manner specified in the agreement”. 

It should be noted however, in either such case, that the employer plaintiff will have to satisfy the court that there is a fair question to be tried and that the balance of convenience does in fact favour the granting of the injunction, notwithstanding the considerations described above. 

In this context, the Supreme Court also noted that:  

The default position in applications for injunctions restraining industrial action should be therefore, that it should be assumed that the case will not go to trial, and the NWL/ Merck criteria should apply, unless there are particular features in the claim which may make it probable that the case will proceed to trial on the issue, and in relatively early course.  It should be a matter for the party seeking that injunction to displace that presumption.” (Paragraph 69, O’Donnell CJ)

In summary, it should be noted that the NWL/Merck criteria require a court, in considering an application for an injunction, to make its best estimate at this point of the respective parties’ cases.  This will normally make it more difficult for an employer plaintiff to secure an injunction, even if it successfully contends that section 19(2) does not apply.  

In circumstances where it was already difficult for an employer to secure an injunction restraining picketing and industrial action, this Supreme Court decision now makes it immeasurably more difficult. 

The content of this briefing is provided for information purposes only and is not legal or other advice.