Prima Faecis...or however you spell it...

My understanding of these prima facie rights are that they are the end point, and that we get there from understanding duty and working out conflicts. I don't see how, if prima facie are the end rights, that there won't be any conflicts. After all, if we called the right to life a prima facie, that's still being challenged, and the challenges that it has been facing over the years haven't diminished. How can we rise to the prima facie? They seem out of reach.