Authority to Change Nosah
Question
What authorizes a Rabbi to make a decision to use a nusah? Don’t we need the Sanhedrin?
Answer
Hazal never state precisely which words one must utter from beginning to end. This is true of Birkath haMazon, Tefilath Shemone ‘Esre, Birkoth Kriyath Shema etc. There are many clear proofs of this fact which I omit here.
The statements of the Hakhamim indicate that one must mention certain ideas in certain berakhoth, or that one must end (the hathima) must consist of certain words (see TB Berakhoth 48b-49a); otherwise, the overall text of the berakoth are a matter of personal choice and preference, which are a function of one’s command of Hebrew, knowledge of pesukim etc.