After examining a "large volume" of secret documents, UK judges rejected allegations that selling arms to Saudi Arabia that could be used in the Yemen conflict was illegal.
The Campaign Against Arms Trade had argued that bombs and fighter jets sold to the Gulf state had been used in Yemen, in breach of human rights law.
The activists failed to prove that there is “a clear risk that the arms might be used in the commission of serious violations of International Humanitarian Law," the court in London ruled Monday when dismissing the case.
The Secretary of State for International Trade, who is responsible for licensing the export of arms, was "rationally entitled to conclude" that the Saudi-backed coalition was not deliberately targeting civilians.
The secret material provided to judges "provides valuable additional support for the conclusion," they said in their ruling.
Shares of BAE Systems, Europe’s biggest defense company, reversed earlier losses and jumped as much as 2.1 percent after the ruling.
The UK manufacturer of fighter jets and submarines was trading up 1 percent at 624 pence as of 11:20 a.m. in London, extending the stock’s year-to-date gain to 5.5 percent for a total value of 19.9 billion pounds. Sales to Saudi accounted for 21 percent of BAE’s revenue in 2016.
According to the United Nations, over 10,000 people have been killed as a result of the war in Yemen. Since the bombing in Yemen began in March 2015 the UK has licensed 3.3 billion pounds worth of arms to Saudi Arabia, CAAT said.
“The judgment today is very disappointing and our client has put in an immediate application to appeal which we hope will be granted," Rosa Curling, a lawyer for CAAT said in a statement.
"The law is clear: where there is a clear risk UK arms might be used in the commission of serious violations of international law, arm sales cannot go ahead."