No countries in the world are yet legislating it.
The exciting development would be if, say, Canada wanted to use a metric system like the JTI in order to assess how its funding is going to be given out for public media. It could be used also by NGOs that are giving grants to smaller media organizations all around the world. Ultimately, it could be incorporated into the algorithms of digital platforms, like Google and Facebook, so that they give a little more weight to authentic journalism and a little less weight to clickbait and fake news.