In case of confusion and controversies, is there an Islamic authority that has a ruling to address the issue?

New and complicated problems arise every now and then. They are almost bound with the time. In case an issue arises, Is there any Muslim body/school who can resolve the issue, by offering their own ruling? How well their ruling is accepted across different countries and among Muslims? I would like to know Sunni School of thought as well Shia schools of thoughts.