The Oxford Union is no stranger to controversy. Over the decades, the prestigious student debating society has hosted a range of deeply divisive figures, from far-right agitators such as Tommy Robinson and Nick Griffin, to Holocaust deniers such as David Irving. It has justified these invitations under the banner of free speech and intellectual challenge, insisting that debate must remain open, however uncomfortable the speaker may be. The decision to invite Namal Rajapaksa to address the Union next week, however, is particularly disappointing – platforming a defender of mass atrocities and putting the welfare of its own students at risk.