How does any social issue become a new policy?

Social Issues typically come about in two ways. Political fabrication, or grassroot interest. They can be instigated through mediums such as special interests (ex. green movement), religion, or ideology.

Through political fabrication, a leader of government can suggest that the issue affects the common good of governed people. This in turn precipitates through the population calling for action and then a bill can be made into law. For instance, the Affordable Care Act was debatably instigated by government. While it was obvious that the previous healthcare system was in need of modernization, not many Americans were talking about nationalizing it.

Grassroots is a more pure from of policy considering social issues. This is when the population with large support finds an issue that is affecting their way of life. Petitions can be signed and sent to their respective Congressmen or leaders of government, and it is upon the leaders decision whether the social issue needs to be signed into law.