Marriage equality is the law in the United States, but there is still a long way to go before true equality is actually a reality. One stumbling block is the stubborn double standard that same-sex couples face when expressing affection in public, as Slate's Mark Joseph Stern points out . Heterosexual couples frequently display PDA without any problems, but same-sex couples holding hands or kissing in public are still criticized — or may even face violent backlash.In a new campaign ad released Sunday, Hillary Clinton promotes her record on LGBT equality, including achievements that include making it easier for transgender Americans to change the gender displayed on their passports. The ad combines statements from some of Clinton's pro-LGBT speeches with images of same-sex couples kissing. The former secretary of state and 2016 Democratic presidential hopeful says in the video, "Gay rights are human rights."The imagery is a powerful one for same-sex-couple visibility, Stern notes, considering what he calls the "distressingly puritanical rules that govern gay PDAs." Being able to show affection for your significant other isn't a privilege that should exist solely for heterosexual couples, and Clinton's campaign recognizes that. The ad is a powerful one, because it demonstrates that she knows there's still more progress to be made for equal rights in the United States. Though Clinton has been criticized in the past for seemingly flip-flopping on marriage equality , this new ad is clearly her way of promising to support LGBT rights if she's elected president next year.