Why didn't Barty Crouch Jr just use Imperio on Moody?

Question

Kidnapping Moody and constantly depending on Polyjuice Potion for an entire year seems like a lot of unnecessary trouble just to get Harry to touch the cup. Why not simply use Imperio instead?

Answer 1

Some of the reasons could be:

• Moody was a very powerful auror and it would have been very difficult to keep him in control for that long. Barty Crouch Jr. was able to overpower him by taking him by surprise, and having help from Wormtail. Even then, he only just managed to do it.

  Wormtail and I did it. We had prepared the Polyjuice Potion beforehand. We journeyed to his house. Moody put up a struggle. There was a commotion. We managed to subdue him just in time.

  Harry Potter and the Goblet of Fire, Chapter 35

• There would be a very high risk of Moody escaping control. Even Harry could do it. Barty Crouch Jr. himself had done it. Later, his father did it. Even a small slip-up, like acting the way his father did in front of Harry, could have raised suspicion and destroyed their plans.

• In fact, though they used the curse on Barty Crouch Sr., they had to remove him from public view when it became too risky. Such an option would be difficult in this case, if needed, and again, someone would need to have impersonated Moody to continue the deception. Even then Barty Crouch Sr. escaped. It would be much safer to keep Moody unconscious.

• Even if he had used the Imperius curse, he would have to ensure himself that he didn't make Moody do anything that would be uncharacteristic of him and would raise suspicion. It would be easier, and would give him more control, to handle any unforeseen situation if he became Moody himself.

Answer 2

The Imperius curse, like all magic in Harry Potter, isn’t foolproof. As Crouch (impersonating Moody) himself explains it in class:

‘The Imperius curse can be fought, and I’ll be teaching you how, but it takes real strength of character, and not everyone’s got it. (…)’

(Goblet of Fire, chapter The Unforgivable Curses)

It is difficult to place a powerful wizard under the Imperius curse, and possibly even more difficult to keep the curse up indefinitely. Harry quickly learns how to shake it off in class, and later even defies Voldemort’s own Imperius curse in the graveyard of Little Hangleton (Goblet of Fire, chapter Priori Incantatem). That Yaxley is able to subdue Pius Thicknesse is considered a great accomplishment:

Yaxley squared his shoulders.

‘My Lord, I have good news on that score. I have – with difficulty, and after great effort – succeeded in placing an Imperius Curse upon Pius Thicknesse.’

Many of those sitting around Yaxley looked impressed; his neighbour, Dolohov, a man with a long, twisted face, clapped him on the back.

(Deathly Hallows, chapter The Dark Lord ascending)

We see several cases where victims of the curse are able to escape it after some time. That includes both Barty Crouches; first the son:

‘But Winky didn’t know that I was growing stronger. I was starting to fight my father’s Imperius curse. There were times when I was almost myself again. There were brief periods when I seemed outside his control. (…)’

(Goblet of Fire, chapter Veritaserum)

Later the father, too:

‘But your father escaped,’ said Dumbledore.

‘Yes. After a while he began to fight the Imperius curse just as I had done. There were periods where he knew what was happening. My master decided it was no longer safe for my father to leave the house. He forced him to send letters to the Ministry instead. (…)’

(Goblet of Fire, chapter Veritaserum)

Alastor Moody is an extremely experienced and capable Auror. Crouch can keep him under control while he is weak, wandless, imprisoned in his own trunk; if Moody has short moments of consciousness in the trunk, that doesn’t do much harm. If, however, Moody were allowed to walk around in the school with a wand (not carrying one would be highly suspicious) and to recover physically, he would very likely be able to fight off the curse and, e.g., alert one of the teachers. That would of course be disastrous to Crouch and Voldemort’s plans. So it seems prudent of them not to rely on the Imperius curse too much.

Answer 3

Barty Crouch Jr. has more control being Moody than Imperiusing the real one.

First of all, and perhaps most importantly, Barty Crouch Jr. would be able to strategically plan his actions much better when doing them himself than having to puppet Moody through them. There's a definite benefit in being able to take over the role of Moody, and do everything himself. He'd be able to take quick, spur-of-the-moment action if the situation requires it, something that an Imperiused person following orders, who of his own will would certainly not be doing anything to help the Dark Lord, would be unable to do as well.

Imperiused people require a lot of micromanaging, and would need to be told what to do fairly frequently. When Harry uses Imperio on Bogrod to make him take them into the vault, for instance, Harry has to make Bogrod put his hand on the door to open it - something Bogrod in his right mind would surely know. Harry isn't good at casting Imperio, so a skilled Dark wizard could certainly do better, but in all the other situations the Imperius Curse is used, it turns people into pliable meat puppets, not cunning strategists.

“Make him press his hand to the door!’ Griphook urged Harry, who turned his wand again upon Bogrod. The old goblin obeyed, pressing his palm to the wood, and the door of the vault melted away to reveal a cave-like opening crammed from floor to ceiling with golden coins and goblets, silver armour, the skins of strange creatures, some with long spines, others with drooping wings, potions in jewelled flasks, and a skull still wearing a crown.” _{^{- Harry Potter and the Deathly Hallows, Chapter 26 (Gringotts)}}

As Moody, Barty Crouch Jr. had to do several things that required cunning and strategy. Only some of these are: Confund the Goblet of Fire and put Harry's name in it, pretend to console Neville so that he could give Neville a book with information that Harry needed, turn the Triwizard Cup into a Portkey, remove the obstacles in the maze so Harry could get to the Portkey cup easier - and all without raising anyone's suspicion. It would be difficult, if not impossible, to make an Imperiused person do that all flawlessly, without attracting suspicion or notice.

In addition, Moody would likely be able to resist the Imperius Curse after a while.

Relying on the Imperius Curse to keep Moody subdued would be foolish. Even if Barty Crouch Jr. was able to keep him mostly under control, which is doubtful (as another answer by chirlu explains well enough) even him gaining clarity for a small amount of time could be fatal to the Dark Lord's plan, as Moody could use his moment of clarity to do any number of things - write a note and leave it somewhere, tell Dumbledore, hide, and these are only a few possibilities out of many.

Answer 4

The answers so far have missed out something. Credit. If it was Barty Crouch Jr. doing all the deeds in order to bring Voldemort's sinister plots to fruition, he could claim that Voldemort was indebted to him. There wouldn't be anybody else in the direct link between Crouch and Harry being given to Voldemort.

As you can see from this quote, credit was very significant for Barty Crouch Jr.:

"The Dark Lord didn’t manage to kill you, Potter, and he so wanted to,” whispered Moody. “Imagine how he will reward me when he finds I have done it for him. I gave you to him — the thing he needed above all to regenerate — and then I killed you for him. I will be honored beyond all other Death Eaters. I will be his dearest, his closest supporter . . . closer than a son . . . ."

_{Harry Potter and the Goblet of Fire - Chapter 35}

Answer 5

Voldemort had motive to procrastinate.

The body restoration spell could have failed spectacularly.

Voldemort's greatest magic is experimental, and he knows from experience that it can have disastrous unforeseen consequences (emphasis added):

'I miscalculated, my friends, I admit it. My curse was deflected by the woman's foolish sacrifice, and it rebounded upon me. Aaah ... pain beyond pain, my friends; nothing could have prepared me or it. I was ripped from my body, I was less than spirit, less than the meanest ghost ... but still, I was alive. What I was, even I do not know ... I, who have gone farther than anybody along the path that leads to immortality. You know my goal -- to conquer death. And now, I was tested, and it appeared that one or more of my experiments had worked ... for I had not been killed, though the curse should have done it. Nevertheless, I was as powerless as the weakest creature alive, and without the means to help myself ...'

---

(Goblet of Fire, chapter 33: The Death Eaters)

Voldemort's horrific "baby" form is another product of his experimental magic:

'... Wormtail was able to follow the instructions that I gave him, which would return me to a rudimentary, weak body of my own, a body I would be able to inhabit while awaiting the essential ingredients of true rebirth ... a spell or two of my own invention ...'

---

(Goblet of Fire, chapter 33: The Death Eaters)

The spell to restore Voldemort's adult body is known magic:

'... it is an old piece of Dark Magic, the potion that revived me tonight ...'

---

(Goblet of Fire, chapter 33: The Death Eaters)

However, spells can interact in surprising ways:

'Interesting effect,' said George, looking down at Crabbe. 'Who used the Furnunculus curse?'

'Me,' said Harry.

'Odd,' said George lightly. 'I used Jelly-Legs. Looks as though those two shouldn't be mixed. He seems to have sprouted little tentacles all over his face.'

---

(Goblet of Fire, chapter 37: The Beginning)

Without knowing how two powerful dark spells would interact, and knowing how much suffering he had already brought on himself with his experiments, Voldemort may have been extremely hesitant to proceed.

"Three may keep a secret, if two of them are dead."

(Benjamin Franklin, Poor Richard's Almanack, 1735)

Through most of Goblet of Fire, Voldemort's location and vulnerable condition is known to only two other people, both of whom are, for all practical purposes, dead. Voldemort's secret is safe because Peter Pettigrew and Barty Crouch, Jr, must themselves remain hidden from the authorities lest they forfeit their lives. Although Voldemort remains physically weak during this time, he is much less vulnerable to discovery now than after he reveals himself to his Death Eaters.

Barty Crouch, Jr, was loyal to Voldemort.

Voldemort considers Barty Jr his most faithful servant (Goblet of Fire, chapter 37: The Beginning). Barty Jr agrees.

Conclusion

Voldemort may have chosen his elaborate plan because of the delay it required, since it allowed him to remain hidden and to postpone a risky magical procedure -- and Barty Crouch, Jr, followed his master's orders.

Answer 6

Another reason not yet given is that the Imperius Curse seems to be detectable by the blank stare of the victim.

Now Snape was head to head with Mundungus in an unfamiliar tavern, Mundungus's face looking curiously blank, Snape frowning in concentration.
"You will suggest to the Order of the Phoenix," Snape murmured, "that they use decoys. Polyjuice Potion. Identical Potters. It is the only thing that might work. You will forget that I have suggested this. You will present it as your own idea. You understand?"

_{Harry Potter and the Deathly Hallows, chapter 33 (emphasis mine)}

While the Ministry may have had some difficulty finding out who was actually Imperiused and who was merely lying that they were after the First Wizarding War, that was after the fact. As evidenced by the above quote and similar passages in the books about Imperiused people, it doesn't seem so hard to detect while the victim is under the Imperius curse.