Buffy the Vampire Slayer, Season 7

[Buffy, Xander and Willow argue about whether to kill the re-demonized Anya.]

Xander:
You think we haven't seen all this before? The part where you just cut us all out. Just step away from everything human and act like you're the law. If you knew what I felt -

Buffy:
I killed Angel!! Do you even remember that?! I would have given up everything I had to be with... I loved him more than I will ever love anything in this life! And I put a sword through his heart because I had to.

Willow:
And that all worked out OK.

Buffy:
Do you remember cheering me on? Both of you! Do you remember giving me Willow's message? "Kick his ass."

Willow [shocked]:
I never said that!

Xander:
This is different.

Buffy:
It is always different! It's always complicated. And at some point, someone has to draw the line and that is always going to be me! You get down on me for cutting myself off but in the end, the Slayer is always cut off. There's no mystical guidebook, no all-knowing council. Human rules don't apply. There's only me. I am the law.

Xander:
There has to be another way.

Buffy:
Then please find it.

[Xander walks out the front door. Buffy turns to Willow, silently asking her help to dispatch Anya.]

Willow:
I can't. I'm sorry. [Buffy grabs a sword and heads outside]