Playing With / Conviction by Contradiction

Following

Basic Trope: Finding a hole in someone's alibi immediately proves their guilt, with no chance for reasonable doubt.

• Straight: Dan was murdered in the subway. Alice says she couldn't have been in the subway at the time of the murder since she knew she would be working overtime, but Detective Bob notices that her metro pass is not where she normally keeps it, meaning that she must have taken it, killed Dan, and commuted away from the scene of the crime. Alice is jailed on this Insane Troll Logic alone.
• Exaggerated: Alice claims she signed into work at 9:00 a.m. sharp the day Dan was murdered. Bob's investigation reveals she signed into work at 8:59':59'' a.m. An arrest is immediately made.
• Downplayed:
  • Detective Bob does not order an arrest on Alice upon learning this, but he does redirect his focus to proving her guilt.
  • Detective Bob only manages to prove Alice committed perjury and forged evidence — she is found not guilty of murder for lack of sufficient evidence.
• Justified:
  • The police are corrupt and keen to close the murder case as quickly as possible via Kangaroo Court.
  • Bob knows she was the culprit, but Alice has an almost completely airtight alibi. She takes pleasure in seemingly being untouchable, but the little slipup she didn't cover up leads to him Spotting the Thread.
• Inverted:
  • Conviction by suspicious lack of contradiction.
  • Or similarly, acquittal by contradiction; Alice confesses to murdering Dan, but is found innocent because her confession has holes in it.
  • Upon being accused, Alice flawlessly recites a Long List of reasons why she could not have been at the scene of the murder. The police arrest her based on this: if she's innocent, why would she memorize all that?
  • Reasonable doubt keeps Alice from being arrested despite having a massive pile of circumstantial but deniable evidence pointing to her.
• Subverted: Bob and the detectives accidentally get the case thrown out by the grand jury in an unopposed hearing for an indictment by forgetting to get any true evidence linking Alice to the crime.
• Double Subverted: ...until Bob finally locates decisive evidence, which he uses to get Alice punished.
• Parodied:
  • Alice is arrested for a contradiction that is completely unrelated to the murder case.
    Alice: I couldn't have been involved in the murder, I was at work when it happened. You can ask my employer.
    Bob: Really now. [cracks fingers] Who announces the instruments in the 2003 re-recording of Tubular Bells, at the end of side A?
    Alice: Uh... some guy? Mike Oldfield? Didn't he make that album?
    Bob: Really? It was Mike Oldfield who was the announcer? That's very strange, because I have a copy of that version right here, and it says the announcer was none other than a certain John Cleese.
    [Alice is reduced to Stunned Silence]
    Bob: Your silence speaks magnitudes. [as another officer handcuffs Alice] You have the right to remain silent. Anything you say can be used against you in a court of law...
  • Alice recounts a full history of what she did that day from dawn to dusk, with excruciating detail provided about every little event. The police later arrest her when they find out that at 2:00 p.m. she was actually talking about the weather with her coworker Earl, not her coworker Smith, as she had claimed.
  • Alice, a ten-year-old, likes to eat veggies (although not broccoli but something less bitter like chickpeas). The other kids on the block think she is an alien Terminator Impersonator out to Take Over the World just because of that.
  • Alice is interrogated as a suspect for murdering Dan even though he died of a heart attack. Bob won't accept in her alibi that she didn't secretly cause it through some form of Applied Phlebotinum that would induce fatal medical conditions in remote targets.
• Zig-Zagged: There are a few holes in Alice's alibi that seem contradictory, but get easily explained away when Bob presses her. Except for one, which he uses to prove her guilt.
• Averted: Bob finds a contradiction in Alice's alibi and explicitly notes that it only means she is still a suspect because it isn't enough to prove guilt.
• Lampshaded: "...wow, I'm impressed. One mistake and I'm in handcuffs."
• Invoked: Alice intentionally provides the minor contradiction to distract Bob from her partner who actually did the crime.
• Exploited: Charlotte is Taking the Heat for Alice, making it seem as though she framed Alice with a convoluted but oh-so-slightly-flawed alibi, and throwing in all the little contradictions that make showy, reputable TV detectives like Bob tick. By the time she's handcuffed, she laughs and announces that Alice is already going by another name in another country, eliciting a Mass "Oh, Crap!" from every officer in earshot — except Bob, who won't be fooled by such obvious lies.
• Defied: Bob does not focus on the minor contradiction in Alice's testimony, reasoning that it seems suspicious, but it's not enough to cast her as guilty. At best, it marks her as someone to observe in more detail.
• Discussed:
  • "You sure this will be a good alibi?" "Don't worry, Bob's an idiot. Just stay with the script and keep any slipups to a low level."
  • "Seriously? I have the clarity of mind to label my husband in the past tense, as you're supposed to do, now that he's dead and you're going to accuse me of murder because of that?"
• Conversed:
  • "I swear, if I were in a Police Procedural, I'd get arrested right away because of how I stutter over important topics."
  • "Alice just said she walked to the subway station one second earlier than she actually did. That is going to be an important clue soon."
• Deconstructed: Alice said something factually wrong about her whereabouts and actions when Bob interrogated her, but it was an innocent mistake: she has memory problems.
• Reconstructed: Bob finds out that Alice made up her memory problems and continues pursuing her: if she lied about one thing, she might well be lying about another.
• Played for Laughs: Alice's inarticulate attempts to correct her misstatements in her alibi are strangely funny.