HS2 Action Alliance (HS2AA) and Hillingdon Council made complaints arguing the UK Government and European Commission failed to conduct a Strategic Environmental Assessment (SEA) for HS2.
The groups say the public were not provided with sufficient information about the environment impacts of HS2 and reasonable alternatives to the project, which the SEA directive requires it to consider.
This is a breach of Article 7 of the Aarhus Convention, which requires effective public participation in plans or programmes relating to the environment, the groups argue.
Councillor Ray Puddifoot, Leader of Hillingdon Council, said: "I believe that the UK's Supreme Court's decision that a Strategic Environmental Assessment was not required in the HS2 consultation process is inconsistent with laws to protect the environment, leaving the UK in breach of the UN Treaty obligations under Aarhus.
"I am therefore delighted that the Aarhus Committee will be investigating this matter."
Lottie Jones of Hillingdon Against HS2, who is also informing the investigation, said: "I have joined forces with Hillingdon Council and HS2AA in taking this case as I feel it's important that ordinary people affected by HS2 are given a voice on such a significant issue.
"I am really pleased that the Aarhus Committee have agreed our right to be heard and we can take a step forward in calling this government to account over the way in which it is planning HS2 and its responsibilities to the environment."
The Aarhus Compliance Committee has ruled that the case should receive a full hearing in Geneva in Switzerland and the next step is hearing how the UK will justify its position to the Aarhus Committee given its duties under the international treaty.
The European Commission is involved in the proceedings because the UK's Supreme Court maintain they are complying with the relevant European Union Directive.
Hilary Wharf, Director of HS2AA said: "This decision is a crucial step in getting the Government to face up to their environmental responsibilities that they have tried to evade by adopting the Hybrid Bill method of getting planning consent for HS2.
"We have always said that the UK Government was wrong but the UK courts have favoured the Government. This UN organisation, Aarhus, has now recognised that our case against the Government needs to be heard."