The SDLP has proposed a Stormont law aimed at preventing the Conservatives from diluting workers' rights when powers are transferred from Brussels.
The party said it would oppose any Tory bid to tamper with devolved Northern Ireland responsibilities when EU directives are repatriated into UK statute as part of a Great Repeal Bill.
A House of Commons library paper found 19,000 EU legislative acts, and another 7,900 UK statutory instruments employing EU law. A total of 180 acts over recent years had EU influence.
The SDLP manifesto said: "We cannot find ourselves in a situation whereby key devolved areas, such as employment rights, are tampered with by the UK Government before people in the North have their say through the Executive and Assembly."
A Brexit white paper from the Government estimated up to 1,000 statutory instruments will be required as part of the transfer of law.
The SDLP proposed tabling a Devolution, Rights and Environmental Standards Bill at Stormont to allow devolved legislators to establish "principled foundations" for a settlement informed by the 1998 Good Friday Agreement.
The manifesto said: "In areas such as employment rights we want to prevent dilution before devolution."
The document stretched to 30 pages.
It covered areas like shaping Northern Ireland special status with the EU, European funding, combating racism and supporting immigration.
Other pledges included:
:: Working to restore the Assembly and Executive at Stormont;
:: Creating greater transparency in the devolved institutions to prevent a repeat of the Renewable Heat Incentive scandal;
:: Opposing cuts to benefits, tax credits and pensions;
:: Campaigning for an anti-poverty strategy;
:: Ending the Civil Service pay freeze;
:: Tackling domestic abuse;
:: Supporting priority funding for social housing and new build programmes;
:: Backing LGBT rights;
:: Addressing the "crisis" in NHS waiting lists;
:: Prioritising investment in third level education and apprenticeships.
