Britain's government has been given the go-ahead to begin deporting asylum seekers to Rwanda and the first flight could leave next week.
Charities and a trade union had launched a challenge against the government's plan, but the High Court denied an injunction to bar the first flight to Rwanda on Tuesday.
"There is a material public interest in the Home Secretary (Priti Patel) being able to implement immigration decisions," Judge Jonathan Swift ruled on Friday.
Swift alleged that some of the risks facing the deported asylum seekers outlined by the charities were small and "in the realms of speculation".
His ruling was welcomed by government officials, with British Prime Minister Boris Johnson calling it good news.
Patel, who has been facing a wave of domestic and international opposition for weeks, has said illegal asylum seekers must either return to their home country or the country from which they came to Britain.
Lawyers for the claimants said Patel's interior ministry had claimed endorsement for the plan from the United Nations High Commissioner for Refugees (UNHCR).
The UN refugee agency on Friday accused Britain of dishonesty. Its lawyer Laura Dubinsky said it "in no way endorses the UK-Rwandan arrangement".
"UNHCR is not involved in the UK-Rwanda arrangement, despite assertions to the contrary made by the secretary of state," she told the court.
Dubinsky said the would-be refugees were at risk of "serious, irreparable harm" if sent to Rwanda, and that the UN had "serious concerns about Rwandan capacity".
Refugee rights groups and a trade union representing UK Border Force personnel have said the plan violates asylum seekers' human rights. They say the British government cannot justify its claim that Rwanda is a safe destination.