An on-going employment tribunal case in Scotland could delay the government's plans to introduce all-women shortlists for parliamentary selections.

The government appears set to delay the introduction of legislation until the case of Lorraine Mann has been completed.

Mann has mounted a challenge to a ruling which prevented her standing as a "job sharing candidate" in the 1999 elections to the Scottish parliament.

She scored a victory in the first round of her challenge when an Edinburgh employment tribunal ruled that being an MSP was a "profession" under the Sex Discrimination Act.

However, the ruling was over-turned in December and Mann has mounted an appeal - with a further ruling expected by November.

The complex case has implications for the route the government chooses to pursue in legislating for all-women shortlists.

The initial plan was simply to list candidate selection as an exemption from the Sex Discrimination Act.

This would overcome the objections raised to Labour's all women shortlists in 1997, which were effectively challenged by an employment tribunal.

Pursuing this route, however, would strengthen Mann's case that being an MP or MSP is a "profession" and open the door to job-sharing and other practices amongst parliamentarians.

Draftsmen are said to examining other ways to make all-women shortlists fireproof, although the proposals will not be brought forward until a final ruling has been made in Mann's case.

Whilst this will mean the legislation will be delayed by several months, it is still anticipated that Labour will have the measure in place in time for the next election.

A proposed alternative to a simple exemption would be to change electoral law to make all-women shortlists legal. However this route is said to open-up other possible problems, such as a challenge from the BNP to permit "all white" shortlists for parliamentary selection.

The government is said to believe that the most problem-free route would be through changing employment law - providing this can be reconciled with Mann's challenge to the Scotland Office.

The move is an attempt to increase the number of women in the House of Commons, following a reduction in the number of women MPs between the 1997 and 2001 elections. Whilst a record-breaking 120 women MPs were returned to the Commons in 1997, this number fell to 115 in June's general election.