Pharmaceutical makers have long promoted their products as a means to enhance or prolong life. Now some have been enmeshed in a transatlantic battle over whether their drugs can also be used to end it. Europe is escalating its war on the U.S. practice of executing inmates with prescription drugs, and they’re making it harder for prisons in the 33 states where lethal injection is legal to acquire their weapons of choice.

The U.S. is one of only two developed democracies to use capital punishment. The other, Japan, executes by hanging. “Not only is capital punishment outlawed across Europe, but European policy is also to work actively for abolition of the death penalty worldwide,” says Sarah Ludford, a member of the European Parliament. “By persuading responsible pharmaceutical companies to supervise their distribution chain and by getting controls on exports from Europe tightened, U.S. prisons’ ability to procure their death machine supplies has been thwarted.”

Lethal injection usually involves three drugs: one to put an inmate to sleep, one to paralyze the muscles, and one to stop the heart. First adopted by Oklahoma more than 35 years ago, that protocol had been little changed until Europe two years ago began limiting drug supplies.

Read More: Lethal Injection