"No means no". It's a familiar mantra, one drummed into our consciousness by campaigners trying to prevent sexual assault. But California's legislators think it needs to go one step further - sexual consent is not just the absence of a no - it should actively require both parties to agree. In other words - "Yes, means yes". There are growing worries about US universities - some figures suggest at least one in five female students are sexually assaulted. So California is now writing the rule into law - at least on state-funded campuses. Will it make a difference? Joining me to discuss the issues are the British lawyer Sophia Cannon and from Lexington in Kentucky Professor Ann Coker who is Chair in the Center for Research on Violence Against Women at the University of Kentucky.