irrecusable
Concise Oxford English Dictionary © 2008 Oxford University Press:
irrecusable /ˌɪrɪˈkjuːzəb(ə)l/
▶adjective rare (of evidence or a statement) not able to be challenged or rejected.
– origin C18: via Fr. from late L. irrecusabilis, from in- ‘not’ + recusabilis ‘that should be refused’.
'irrecusable' also found in these Oxford entries:

