John Proctor utters this line. He is against the witch-trials and has called the accusations false, called the girls making them frauds, and turned his ire on the court as well.
When the court fails to see the truth of his claims and insists on standing by its authority, Proctor declaims against the court.
"I like not the smell of this authority" is a line suggesting a rottenness in the court.
After raising serious doubts about the validity of the court's prosecution of those accused of witch-craft (including his own wife), Proctor is amazed, disappointed and angered that the court refuses to admit to its mistakes. Danforth stands on his authority and articulates his position.
He says that the court cannot allow its authority to be questioned. For this reason, he feels he must work against Proctor's claims. This leads to the scene where Proctor confesses to adultery with Abigail then Elizabeth is brought in to confirm the truth of this confession.
She fails to confirm Proctor's statement and her husband is then condemned.
Proctor, the principle enemy of the witch-hunt, has become its ultimate victim.