In many African countries, it's been a particularly tough time to be an opposition presidential candidate. Over the past several years, while some attempts to wrest power away from longtime African presidents have succeeded at the ballot box, many others have failed. Some of these failures have led to dire consequences for challengers, including arbitrary arrests and incarcerations. Today in Uganda, for example, President Yoweri Museveni — in power for the past 30 years — was sworn in for another term after a tumultuous election campaign, during which the main opposition candidate was placed under house arrest and social media channels were blocked.