The standard definition of "deontology," in moral philosophy, is the view that the morality of an action is to be judged by duty or rule independent of the consequences of the action.
Or, in the popular cliche, the view that "the end never justifies the means."
The standard example of a deontologist is Immanuel Kant.
The standard Philosophy 101 type example involves the serial killer looking for his next victim, and the honest man who knows where the potential victim is hiding, and wonders whether it is permissible to lie to save that life.
But in the 1990s Barbara Herman wrote a book apparently intended to overturn the way moral philosophy has been taught in survey courses for generations.
I've just learned of this book, because ... well ... news from academia reaches me slowly.
At any rate, the book is THE PRACTICE OF MORAL JUDGMENT (1993).
That's a photo of her above.
Here's a link to the book, much of which can be read on line.