Mr Lee subsequently brought a claim for direct and indirect discrimination on the grounds of sexual orientation, and religious or political opinion.  At first instance the district judge in Northern Ireland (where the case was raised) found there was direct discrimination both on the grounds of sexual orientation and religious belief or political opinion.  Mr Lee was awarded £500 damages. 

The McArthurs appealed to the Northern Ireland Court of Appeal.  That appeal was unsuccessful. 

The question for the Supreme Court was whether it was unlawful discrimination for the bakery to refuse to supply with cake because of the sincere religious beliefs held by the McArthurs.  If the court found it was, then questions arose as to the rights of the McArthurs to freedom of religion and freedom of expression under articles 9 and 10 of the European Convention on Human Rights ("ECHR"). 

It was argued for the bakery that the evidence was that the bakery would have supplied Mr Lee with a cake that did not contain a message supporting gay marriage and that they would not have supplied a cake with such a message to a heterosexual customer.  The objection therefore was to the message not the messenger.  In relation to the associative discrimination claim which relied on the reason for the refusal being the fact that Mr Lee was likely to associate with the gay community, it was argued that there was no evidence of the bakery ever discriminating in that way - instead there was evidence of them both employing and serving gay people and treating them in a non-discriminatory way.

In light of these arguments the Supreme Court concluded that there was no discrimination on the grounds of sexual orientation, overturning the findings of the Irish courts.  The district court judges finding of discrimination on the ground of religious belief was also overturned on the basis that the less favourable treatment that is prohibited by legislation must be on the grounds of the religious beliefs of someone other than the person meeting out the treatment.  The religious beliefs here were those held by the McArthur family, the alleged discriminators, and accordingly no discrimination had occurred.

The question of discrimination relating to political opinion was not so straight forward.  While a similar argument could be made that it was not Mr Lee or anyone he associated with that the McArthur's objected to, rather it was the request to promote the support of gay marriage on the cake, the Court felt that the message on the cake was so closely associated to the obvious political beliefs of Mr Lee that it was arguable that discrimination had occurred.  This meant that the Court had to consider what effect the McArthur's ECHR rights had on the discrimination legislation - domestic legislation requiring to be read in a way which is compatible with their ECHR rights to freedom of religion and freedom of expression.

The Supreme Court held that the legislation should not be read in a way which compelled the bakery to express a message with which they disagreed, unless there was justification for doing so.  While the bakery could not refuse to provide a cake to Mr Lee because he was gay or because he supported gay marriage, the Court was of the view that that fact did not justify obliging them to supply a cake iced with a message with which they profoundly disagreed. 

In terms of the letter of the law, this judgement makes sense - for discrimination to occur there must be an objection to the messenger and not the message.  This does have to come with the usual warning that cases such as this will turn on their facts.  In similar cases it is possible that the message requested (whatever that might be) is so closely associated to the protected characteristic of the "messenger" requesting it that a refusal would have been found to have been discriminatory.