In the case, Okoro v (construction company) Taylor Woodrow, the end user imposed a ban on the number of agency workers employed at a particular construction site.
The workers alleged that the ban was imposed for racially discriminatory reasons.
The issue that arose was whether the alleged act of discrimination took place when the ban was imposed, or whether it was a 'continuing act'.
This had implications for when the workers could bring a tribunal claim – if it was a continuing act, time would not begin to run while the ban remained in place.
The Court of Appeal held that on the facts of this case the ban was a one-off, not a continuing act and that a claim had to be made within three months.
Tom Kerr Williams, employment partner at law firm DLA Piper said: "This will be of comfort to businesses who use agency workers. If a ban is imposed, the end user may in some circumstances be at risk of a discrimination claim by the affected agency workers.
"However, that claim would need to be brought within three months of the ban being imposed. If the Court of Appeal had reached the opposite conclusion, the agency workers would potentially have been able to bring the claim many months or even years down the line as long as the ban remained in place.
"The difficulty then faced by employers is how to prove that the decision to ban the workers was not made for discriminatory reasons. The more time that passes, the more likely it is that the individual who made the decision to ban the workers may have moved on, which may make proof more difficult. The Court of Appeal's decision today limits the potential risks for users of agency staff in this respect.
He added: "Companies should, however, continue to be wary in circumstances where the banned workers present themselves for work and are turned away as a result of the ban. If this occurs after the date of the ban, it may amount to a separate and distinct act which could start the three-month time limit running again."