What is the Catholic process for establishing orthodoxy?

After reading and doing light research concerning [this question](https://christianity.stackexchange.com/questions/66072/is-mercy-above-orthodoxy) , I'm compelled to ask, what is the process for establishing the orthodoxy of a belief in the Catholic church today? [From m-w.com](https://www.merriam-webster.com/dictionary/orthodoxy) : > 1 : the quality or state of being orthodox
> 2 : an orthodox belief or practice [From Wikipedia](https://en.wikipedia.org/wiki/Orthodoxy) : > Orthodoxy is adherence to correct or accepted creeds, especially in religion. In the Christian sense the term means "conforming to the Christian faith as represented in the creeds of the early Church." The first seven ecumenical councils were held between the years of 325 and 787 with the aim of formalizing accepted doctrines. Based on these two references (and my own, personal understanding), *orthodoxy* is a belief established by a religion, presumably based on its source canon. Thus, the Biblical "Thou shalt not kill" might be considered doctrine, and therefore an accepted/official belief of the church that capital punishment is unacceptable as a form of punishment would be considered an "orthodox belief" or "orthodoxy." What, then, is the official procedure in the Catholic church for establishing a belief (new or modified) as *orthodox?*