Who has the authority to change the procedure for vedic rituals and under what circumstances?

Question

Being born in a smartha brahmana family, I have had the chance to observe and also perform many vedic rituals at home and other places, starting with nitya karmas like sandhyavandanam to major homams/yajnas like Ganapathi, Navagraha, Sudharasana, Mrtyunjaya homa. As I grew familiar with the rituals over the years, I have begun to notice that the procedure for the same rituals have become modified here and there, depending on which Vaadhyaar (brihaspati/purohit) is guiding the execution. Even sandhyavandanam seems to have been modified with some mantras which were never part of it since my grandfather's days.

So my question is who decides on changes to rituals, for what purpose and by what authority? Under what circumstances can they be justified?

Answer 1

Note: This is not an answer to the question, but rather an explanation as to why there can ever be no such authorities to standardize any form of traditions or customs, based on a broader view of ever-changing nature of everything.

From a broader perspective, taking into account the evolution of early Indic religions to the present forms of Hinduism and other schools like Jainism, the procedure of rituals (Puja) and sacrifices (Yajna) have always been subject to change. Each school/sect of contemporary Hindu religion claims and prioritizes its own flavour and mix of customs and traditions which has been shaped to its present form over the course of centuries.

There is no single authoritarian school which can claim the complete authority of any set of universal standardized (Vedic) rituals and sacrifices. In fact, there are even sects which have few contradictory forms of dharmic rituals who claim themselves to be the absolutely right one.

To give a historical perspective, the contemporary or even classical forms of Hinduism have diverged a lot from the actual oldest forms of Vedic religion which started flourishing roughly from 2000 BC, right from the beginning of Aryan Migration into the Indo sub-continent who brought in the Proto-Vedic religion. A lot of changes in culture and religion have occurred since then, with rise and fall of different schools of Indo-religions.

For example, see: The changing nature of Vedic offerings

---

To briefly give my (opinionated) answer to your question, it is better if one focuses only on the true duties at hand pertaining to his job, society and family (& friends) rather than any acts of pleasing any Devas or dead ancestors.

Quoting a related verse from Bhagavat Gita:

यामिमां पुष्पितां वाचं प्रवदन्त्यविपश्चित: ।
वेदवादरता: पार्थ नान्यदस्तीति वादिन: ॥2.42॥
कामात्मान: स्वर्गपरा जन्मकर्मफलप्रदाम् ।
क्रियाविशेषबहुलां भोगैश्वर्यगतिं प्रति ॥2.43॥

Translation:

Men of small knowledge are very much attached to the flowery words of the Vedas, which recommend various fruitive activities for elevation to heavenly planets, resultant good birth, power, and so forth. Being desirous of sense gratification and opulent life, they say that there is nothing more than this.

Answer 2

All the rituals available in Hindu dharma having a certain reason behind all of them. There is nothing to mention that some particular persons have the authority to change the rituals.

But, sometimes it is not possible to perform all the Vedic rituals while doing some religious acts. So there are some alternates already given there for every religious act. whenever there are some needs to modify in any ritual we can do it with the advice of experts or bramhana who knows.

In ramayana when lord rama was doing Aswamegh Yagn(Havan), he kept the statue of Mata sita with him in place of the real one because when doing these kinds of ceremonies, need to sit with the wife, but at that time Rama was alone, and his wife mata sita was away, So he took this step.

In mahabharata, lord Krishna also guided in such circumstances. i.e. In some ceremonies, you need to speak the name of your Ancestors, but if you don't know then you can use the name of Brahma-Vishnu-Mahesh, with the spirit, that you are speaking about your ancestors. These kinds of so many alternates available in Hinduism, which is pre-defined in Veda.

So modification in rituals is based on circumstances, but the way of modification should according to exhibited in dharma, and anyone can do this. There is not any kind of authority.