Europe's highest court has ruled that a lifetime ban on gay men giving blood "may be justified" in certain cases.
However, it said it had to be proportionate and that national authorities had to be able to establish that such men were in fact at high risk of acquiring diseases such as HIV.
The European Court of Justice ruled that member states should establish if there were not more accurate detection techniques or "less onerous" ways of ensuring that recipients of donated blood were protected, rather than banning gay men for life from giving blood.
Ireland and a number of other countries maintain a lifetime ban.
The law in the UK was changed in 2011 so that a one-year ban would be established instead.
The Government is considering whether or not to follow the example set by the UK and others and introduce a one-year ban instead of a lifetime ban.
In a statement this morning, Minister for Health Leo Varadkar said: "Any decision will be guided by medical and scientific evidence and best international practice.
"I do not see this as an equality issue.
"We must always remember that the risk being taken is by those who receive blood, not those who donate it."
The ECJ was examining the case of a French man who, in April 2009, was refused to be allowed give blood to the local blood donation authorities in Strasbourg.
The man - Geoffrey Léger - had argued that the refusal discriminated against him on the grounds of sexual orientation.
French judicial authorities then sought guidance from the ECJ in Luxembourg that a lifetime ban in France on donations from men who had sex with other men was compatible with EU law on blood donations and with the Charter of Fundamental Rights.
In today's ruling, the court effectively ruled that a lifetime ban "may be justified" but only in cases where it was clearly established that a person was, indeed, at high risk of contracting infectious diseases such as HIV and hepatitis.
The court also queried whether the statistical prevalence in France of HIV infection among men who have sex with other men was still accurate.
The court noted that between 2003-2008 almost all HIV infections involved sexual relations, and almost half of those involved men who had sex with other men.
That meant the infection rate among homosexual men was 200 times greater than that among the heterosexual population.
In a statement the court said: "In France, the prevalence of HIV in the group constituted by men who have had sexual relations with other men is the highest among all the states in Europe and Central Asia."
The local judicial authorities in Strasbourg would therefore "have to ascertain whether, in the light of current medical, scientific and epidemiological knowledge, that data is reliable and still relevant".
Even if there was a higher risk of HIV infection among French gay men, French authorities would have to decide where banning them from giving blood for life would not discriminate against them on the grounds of sexual orientation.
If the French authorities maintained that discrimination, it would have to ensure that any limitations in the Charter of Fundamental Rights were imposed "only if they are necessary and genuinely meet objectives of general interest recognised by the EU, or the need to protect the rights and freedoms of others".
The court suggested that current medical advances and detection techniques meant blood recipients already had "a high level of health protection".
"The national [French] court will have to verify whether such techniques exist, it being understood that the tests must be carried out in accordance with the most recent scientific and technical procedures."
A Department of Health spokesman said this morning that a detailed analysis of the latest international evidence will be contained in a new recommendation on blood donations from men who have sex with other men that the Irish Blood Transfusion Service is preparing for the department.
