The High Court has cleared the way for construction of the Sh4.4 billion, 52-kilometre Mau Mau Road through the Aberdare National Park and Forest after dismissing a constitutional petition that sought to stop the flagship infrastructure project on environmental grounds.
A three-judge bench comprising Justices Lucy Gacheru, Bernard Eboso and James Olola on Friday ruled that the environmental safeguards adopted for the project were adequate if fully implemented throughout construction and operation.
The judges said the dispute required balancing infrastructure development with environmental protection under the constitutional principle of sustainable development.
"The petitioner did not prove violations of Article 69(1) of the Constitution," the judges ruled, finding the evidence presented did not establish that the State had breached its constitutional duty to protect and conserve the environment.
The court verdict ends a long-running legal battle over the road linking Nyeri and Nyandarua counties through the Aberdare ecosystem, one of Kenya's most important water towers.
The petition was filed by the East Africa Wildlife Society, Kenya Forest Working Group, Africa Centre for Peace and Human Rights and conservationist Lempaa Suyianka.
Plans for implementation of the Sh4.4 billion project known as Mau Mau Lot 4: Ihithe-Ndunyu Njeru Road, traversing the Aberdare National Park and the Aberdare Forest Reserve, were rolled out in 2009 as part of the Vision 2030 flagship projects of attaining a sustainable safe road network.
The implementation was delayed for over 16 years following ecological concerns raised by civil society groups and environment conservationists.
The tussle, as it can be picked from the court papers, was between Government's push for economic development against protection for nature on the part of the petitioners.
The dispute escalated in January 2024 after President William Ruto insisted that his administration would proceed with the works of upgrading and expansion of the road and open it for public use.
The petitioners sued arguing that the road would cause irreversible environmental, economic and cultural damage to the Aberdare ecosystem and threaten endangered wildlife, including the critically endangered Mountain Bongo.
The petitioners also told the court that the Aberdare ecosystem, which is on Kenya's tentative list for UNESCO World Heritage status, supports millions of people, livestock and wildlife by providing water and other ecological services.
They sought a permanent injunction stopping construction, arguing the project violated the constitutional right to a clean and healthy environment and the State's obligation to conserve forests and biodiversity.
Signpost of Aberdare National Park.
Photo credit: File | Nation Media Group
The case also challenged the legality of developing infrastructure within protected forests and national parks. The petitioners' claimed that for the State to achieve the development goal on the road project, it must destroy 25 kilometres of closed Aberdare canopy forest, thereby destroying the wildlife Park and the Reserve, and ruining its unique biodiversity.
Kenya National Highway Authority (KeNHA) opposed the petition and maintained that the project complied with environmental law and constitutional requirements.
The highways authority told the court that the road forms part of the government's Vision 2030 programme to expand the country's transport network while supporting economic development.
It said environmental experts had assessed the project before construction began, public participation had been conducted and mitigation measures incorporated into the Environmental Impact Assessment study.
KeNHA further argued that the project would have limited environmental impacts and would not permanently alter the Aberdare ecosystem as alleged by the petitioners.
The court held that concerns raised by the conservation groups and other stakeholders had been addressed through the project's environmental assessment process and did not justify halting implementation.
It also rejected arguments challenging the Environmental Impact Assessment licence issued for the road. KeNHA said the project would not change the eco-system as alleged by the petitioners
The judges said the legal provisions relied upon by the petitioners were not in force when the licence was granted and could not be applied retrospectively.
"It would be improper to require compliance with legal provisions that had not yet taken effect at the time the licence was issued," the bench held, allowing KeNHA to proceed with construction of the long-delayed road subject to full implementation of the environmental safeguards outlined for the project.
The judgment marks a significant shift in the dispute after the same bench previously rejected KeNHA's attempt to have the case struck out on jurisdictional grounds before hearing the merits.
At that stage, the judges held that the petition raised constitutional questions extending beyond the jurisdiction of the National Environment Tribunal.
“Apart from the issue of the Environment Impact Assessment licence, the petition raises various constitutional issues,” the judges said in the earlier September 2025 ruling.
“The issues raised in the petition touch on violation of various constitutional rights such as the rights to a clean and healthy environment, depletion of tree cover, climate change and threat to biodiversity among others.”
