Yeah, it's in season 2, episode 13 - Bartlet's Third State of the Union. Its the night of the SOTU address and TWW is hosting a special edition of "Capitol Beat" with Mark Godfrey (Did anyone else happen to notice that they used the News at Ten music during the titles!?!)
Here is the scene:
CUT TO: INT. WEST WING LOBBY - NIGHT
Toby and Congressman Shallick are on the dais of Capitol Beat. Ginger is in the crowd.
SHALLICK
Excuse me...
TOBY
I don’t...
SHALLICK
Excuse me. But this White House uses the first amendment to protect flag burning, to protect
pornography, to ban school prayer. Why when the second amendment clearly says that the federal
government will not infringe upon a citizens...
TOBY
Because it doesn’t...
SHALLICK
...right to keep and bear arms...
TOBY
It doesn’t barely say that.
SHALLICK
Toby!
TOBY
In fact it doesn’t say that at all. The only way it says that at all is if you remove some
words from it.
SHALLICK
Oh, look. Will you...?
TOBY
It says a well-regulated militia, being necessary for the security of the free state...
the government shall not infringe. The words regulated and militia are in the first sentence. I don’t think the Framer’s were thinking of three guys in a Dodge Durango.
SHALLICK
Well, you don’t really know what the Framers were thinking, do you?
TOBY
No. But I do know that if you combine the populations of Great Britain, France, Germany,
Japan, Switzerland, Sweden, Denmark and Australia you’ve got a population roughly the size of the United States. We had 32,000 gun deaths last year and they had 112. Do you think it’s because Americans are more homicidal by nature? Or do you think it’s because those guys have gun control laws.
MARK
We’re going to talk to some people and hear answers to that question. You’re watching a special expanded edition of Capital Beat coming live from the West Wing of the White House. We’ll have more after this.
Hope this helps!

JOSH: I'm thinking of firing you.
DONNA: You fired me twice already tonight--I'm impervious.