A challenge to a law that allows employers to force workers into retirement at 65 has been referred to the European Court of Justice.
Employers can insist employees over 65 must retire
Anti-ageism campaigners asked the High Court to look into the legality of mandatory retirement ages.
The action, launched by the Heyday organisation, has now been referred to Europe for legal guidance.
The government says it acted properly in implementing European rules allowing employers to retire people at 65.
Heyday, part of the National Council on Ageing, says the new government regulations amount to "a de facto mandatory national retirement age".
Its challenge to the law is being backed by Age Concern.
Lawyers for Heyday told the High Court the challenge to the rules was especially important because of the rising number of people working beyond 65 who could be forced into retirement.
Mr Justice Davis, Heyday's lawyers and the government agreed that the case should be referred to Europe on a number of issues.
They will be presented to the judge in January.
The new age discrimination laws came into force in the UK in October in the biggest single change to employment practices in 30 years.
The new laws - the Employment Equality (Age) Regulations 2006 - are the result of a European directive on employment.
They make it unlawful to discriminate against workers under the age of 65 on the grounds of age.
The rules affect recruitment, training, promotion, redundancy, retirement, pay and pension provision.
But Heyday argues the regulations contravene the European Equal Treatment Directive because people over 65 are left without the right or choice to work.
Robin Allen QC, for Heyday, said around 380,000 people over the age of 65 were employed in the UK.
He said up to 25,000 of these were facing retirement against their wishes.
This was "effectively giving these people second-class status because they have no protection against discriminatory decisions to retire them", he said.
The government is contesting the case and maintains it has fully and properly implemented the rules and has already promised to review the mandatory retirement age in five years.
But David Pannick QC, for the Department of Trade and Industry, agreed it should be referred to Europe on certain preliminary issues.
He added that Trade Secretary Alistair Darling would be reviewing the regulations in 2011 to assess their impact.
Heyday's challenge has been adjourned pending a ruling from the European court.
Any individual claims lodged with employment tribunals by people claiming to be the victims of forced retirement at 65 will also be adjourned pending the ruling.
Mature workers are good for business and the economy, Heyday argues.
It claims company profits would rise between £50 million and £110 million if the new rules were scrapped.