The much maligned Manusmriti reserves the strictest sanctions for Brahmins.
There are many citations in the Manu Smriti where these are mentioned.
In general, punishment for a Brahmin is thousand fold for an offense than what is being sanctioned for a Sudra.
In this article we shall see how a Brahmin is declared as an Outcast in one instance, which is very serious.
That instance is Upanayana, wearing of the Sacred Thread)Ceremony)
36. In the eighth year after conception, one should perform the initiation (upanayana) of a Brahmana, in the eleventh after conception (that) of a Kshatriya, but in the twelfth that of a Vaisya.
37. (The initiation) of a Brahmana who desires proficiency in sacred learning should take place in the fifth (year after conception), (that) of a Kshatriya who wishes to become powerful in the sixth, (and that) of a Vaisya who longs for (success in his) business in the eighth.
38. The (time for the) Savitri (initiation) of a Brahmana does not pass until the completion of the sixteenth year (after conception), of a Kshatriya until the completion of the twenty-second, and of a Vaisya until the completion of the twenty-fourth.
39. After those (periods men of) these three (castes) who have not received the sacrament at the proper time, become Vratyas (outcasts), excluded from the Savitri (initiation) and despised by the Aryans.
40. With such men, if they have not been purified ac cording to the rule, let no Brahmana ever, even in times of distress, form a connexion either through the Veda or by marriage. “
Manu Smriti Chapter 2:31;39