For three days this week, starting today, lawyers representing several TUC affiliated unions will be lining up in the High Court as the unions get ready to argue that new equality regulations are allowing pension schemes to discriminate against lesbian and gay workers.

The unions have sought the judicial review, backed by the TUC, because they believe that the regulations - which came into force last December, and which seek to outlaw discrimination on the grounds of sexual orientation in employment and work-based training - are not being implemented as they should be under the EU Employment Equality Framework Directive.

Six unions (Amicus, UNISON, transport union the RMT, the National Association of Schoolmasters Union of Women Teachers, the Public and Commercial Services Union, and NATFHE, the University and College Lecturers' Union) argue that aspects of the Government's Employment Equality (Sexual Orientation) Regulations 2003, which are meant to give lesbian and gay people extra protection under the law, have actually ended up discriminating against them.

TUC General Secretary Brendan Barber said: "The sexual orientation regulations have made a real difference, giving gay people proper legal protection at work for the very first time. But it's a pity that what should have been a cause for union celebration has been dampened by the Government's decision to bar lesbians and gay men from receiving pensions from certain schemes.

"What is essentially a good law has been made less effective than Europe intended it to be. It's not unreasonable for lesbian and gay workers to expect true equality with their heterosexual colleagues, but if this is to happen the Government must back down and agree to a change in the law."

The most significant aspect of the legal challenge is based around regulation 25 which relates to pensions. The unions believe that because it allows UK pension schemes to continue to discriminate in favour of married people, the regulation is allowing indirect discrimination against gay people as they are not able to marry their partners.

Because most public sector schemes still only give benefits to married partners, and around a quarter of private sector pensions schemes do not provide pensions to unmarried partners, the unions are concerned that large numbers of gay and lesbian workers are missing out. The unions are also arguing that apart from a misinterpretation of the EU Framework Directive, the Government's proposed regulation may also be a breach of the Human Rights Act 1998.