Environmental campaigners are to take a Stormont department to court over alleged air quality failings.
Friends of the Earth has teamed up with The PILS Project for a legal challenge at the High Court in Belfast against the Department for Infrastructure.
They said the case is in relation to a long-running and dangerous air quality failing.
The case is expected to proceed to a full hearing in June.
They contend that hundreds of thousands of diesel cars in Northern Ireland have not received a legally compliant exhaust emissions test at government-controlled MOT vehicle testing centres.
The groups are raising serious air pollution concerns caused by diesel emissions and have issued legal proceedings against the department over its “recurring failure to identify dangerous emissions levels during MOT testing”.
Their legal team will argue that in failing to fully test the emissions of diesel cars in Northern Ireland during MOT testing, the department has breached its duties not only under vehicle testing law but also its duties to protect public health and the health of Northern Ireland’s biodiversity and wildlife habitats.
James Orr, director of Friends of the Earth NI, claimed the department has “consistently failed to comply with the law”, describing the situation as “nothing short of a major scandal”.
“The science is clear, the law is clear – there is a duty to test emissions in order to protect both public health and the health of habitats,” he said.
“We are taking the government to court because we all have a right to breathe clean air.”
PILS director Maria McCloskey said: “This is not just a case about diesel emissions.
“It is about air quality, environmental protections, and about a fundamental failure of our government to fulfil its legal obligations since 2006.
“This case potentially impacts every single person living in Northern Ireland. It is, at its core, a public health issue.
“We at PILS are pleased to be able to offer our support to Friends of the Earth NI in this vitally important legal challenge.”
A spokesperson from the Department for Infrastructure said: “The department is aware legal proceedings have been issued and shall not be commenting further in advance of the High Court hearing.”