Liberty's too precious a thing to be buried in books, Miss Saunders. Men should hold it up in front of them every single day of their lives and say, "I'm free to think and to speak. My ancestors couldn't, I can, and my children will."
—Jefferson Smith, doing Eagle Land proud
A senator dies in the middle of his term, and the state Governor has to pick a replacement. The crooked political machine would like one candidate, but this man is already known to take positions unpopular with the populace of that state; there are petitions to pick a radical for the office.
The Governor decides to Take a Third Option: He picks someone who is highly idealistic but inexperienced in politics, whom he thinks the political machine can keep under control. This person, this new senator, is Mr. Jefferson Smith, his son's Scout Master.
Mr. Smith gets to meet his idol, the other senator for his state, who did great things for the state many years ago and who was a personal friend of Smith's father. He's controlled by the machine now, but Mr. Smith isn't really aware of the machine yet.
Once in Washington, he also meets his chief of staff/secretary – a very beautiful, intelligent Femme Fatale. She does have a heart of gold, but she's an utter cynic.
Now, there is one problem the state machine has with Mr. Jefferson Smith. Mr. Smith has one issue he supports – building/improving a Boy Scout camp by a major river in the state. But one of the main goals of this machine is to dam the river (to produce profit for the machine boss, who owns some of the land), which would wipe out many of the natural attractions Mr. Smith hopes to preserve. So, the senior senator and his secretary have to prevent Mr. Smith from voting against the dam, decoying him away from a session where a crucial preliminary vote on the issue is held by sending him on a date with the senior senator's daughter.
Mr. Smith tries to protest the decision within the Senate, but when he yields the floor to the senior senator of his state, he is framed for ethics violations and it is moved that the Senate should consider expelling him. He almost resigns, but his secretary begs him to fight, asking, what would the Boy Scouts he led before becoming junior senator think of politics if he quit now?
So, he doesn't quit. Instead, he holds a very long filibuster, never yielding the floor, never stopping, reading the Bible and the Constitution and the rules handbook, all to buy time for his supporters to send signs of his support. His supporters – many of them too young to vote – do try to show their support, but the machine is actively fighting them...
Eventually, Bags of Letters do flood in, but the machine has successfully swayed public opinion through the media, and the most of the public is against Smith. He declares his intention to keep on fighting in an impassioned speech about how sometimes lost causes are the only ones worth fighting for, then collapses from exhaustion. Overcome by guilt, the senior senator has a Villainous Breakdown. Smith is vindicated.
- Abraham Lincoln: The Lincoln Memorial is an important part of a few scenes.
- Adorkable: Mr. Smith himself. Especially when he's around Susan Payne, who he has a crush on at first.
- Adult Child: Smith shows many traits of this
- Affably Evil: Taylor
- The All-American Boy: Mr. Smith is a perfect grown-up example, as well as all the Boy Rangers.
- Badass Nickname: Paine is known as "The Silver Knight"
- Bags of Letters: Mr. Smith expects his filibuster to sway public opinion in his favor, but he is presented with bags of letters that reveal public opinion has turned against him. The mass of letters almost makes Smith lose hope.
- Bastardly Speech:
- Paine's speech near the end is one of the best.
- Taylor criminalizing Mr. Smith using his media machine is basically this trope on a enormous level
- Blood on the Debate Floor: Sort of, at the end, when Sen. Smith is dizzy with exhaustion and dehydration after having talked on the floor of the Senate for 24 hours.
- Broken Pedestal: Senator Paine
- Character Filibuster: Literally. Never before has a political filibuster been so dramatic.
- Collapsed Mid-Speech: Mr. Smith does this at the climax of the film.
- Corrupt Corporate Executive: Taylor is a newspaper magnate by trade.
- Corrupt Politician: Paine
- Country Mouse: Jeff Smith. Many Frank Capra protagonists are in this mold.
- The Determinator: Mr. Smith. "You think I'm licked. You all think I'm licked. Well, I'm not licked. And I'm going to stay right here and fight for this lost cause. Even if the room gets filled with lies like these, and the Taylors and all their armies come marching into this place."
- Did Not Do the Research: The filibuster scene. Between 1919 and 1975, a filibuster could be stopped by a vote of two-thirds majority of all senators present (after 1975, it was changed to three-fifths of all total senators: 60). In the movie, the Senate majority and minority leaders can be seen collaborating with each other against Smith, implying that the entire Senate is against him, but somehow powerless to stop him.
- Eagle Land: At first glance a Flavor 1, with the idealistic Jefferson Smith visiting the Lincoln Memorial and saying things like the page quote. However, the movie also shows bosses like Taylor owning senators like Paine and manipulating them for their corrupt ends. This pushes the movie closer to the Mixed type.
- Embarrassing First Name: Clarissa Saunders.
- Fainting: Smith collapses of exhaustion during his filibuster
- Fallen Hero: Paine, who was once a crusading reformer like Smith's father but at some point in the past sold out to the Taylor machine.
- Fan Service
- Femme Fatale
- The Government
- Government Conspiracy
- Guile Hero: Smith
- Heel Face Turn: Sen. Paine; see Villainous Breakdown below.
- Hero with Bad Publicity: Smith's approval ratings drop heavily in his home state during the filibuster.
- Highlighted Text: The film uses this device multiple times on various newspaper headlines and articles.
- Holding the Floor
- Hot and Cold: Saunders. She warms up to Mr. Smith over the course of the story.
- I Did Not Say That Mr. Payne Was One Of The Men In That Room
- Incorruptible Pure Pureness: Jefferson Smith.
- Intrepid Reporter: Diz
- Just in Time
- The Mole: The secretary, sort of.
- Noble Demon: Sen. Joseph Harrison Paine
- Nobody Poops: Smith's filibuster lasts 26 consecutive hours, during which he cannot sit down or leave the room. There are certain bodily functions that cannot be delayed for 26 hours. In Real Life, Strom Thurmond had to purposefully dehydrate himself for a full day in a sauna before his record-breaking filibuster (24 hours, 18 minutes against the 1957 Civil Rights Act) so that he would not have to go to the bathroom, and, at one point, even forced a page to hold a bucket outside the Senate while he pissed in it... one foot still on the Senate floor.
- Obstructive Bureaucrat: Congress itself is described like this.
- Paparazzi: The D.C. press. Justified, because they are very cynical about politics.
- The Plan
- Platonic Life Partners: Diz and Saunders
- Post Dramatic Stress Disorder: happens a little earlier than Jeff would have liked.
- Propaganda Machine
- Reasonable Authority Figure: The Vice President
- Scout Out: The "Boy Rangers" after the Boy Scouts of America refused to participate.
- Sesquipedalian Smith: Jefferson Smith
- Sliding Scale of Idealism vs. Cynicism
- Strawman News Media: Type 1!
- Take a Third Option: The Governor's selection of Mr Smith.
- Throwing Out the Script: A Capra staple trope.
- Unwitting Pawn
- Villainous Breakdown: "Expel me! Not that boy! I'm not fit to be a Senator! I'm not fit to live!"
- Washington DC
- We Need a Distraction
- Where the Hell Is Springfield?: The state represented by Senator Jefferson Smith is not named. (Though it's supposed to be Montana.)
- Wide-Eyed Idealist: Dear Wide Eyed Jefferson Smith.
- Would Hurt a Child: Taylor's thugs