Harry Potter managed to successfully use it on Amycus Carrow without legal consequences as well as a result of this legalisation, shortly before the Battle of Hogwarts on 1 May 1998.
Cruciactus curse that was cast by Harry on Bellatrix didn't work because using an unforgivable curse requires a lot of power and having a bad motive. There is a reason they are called unforgivable curses.
In Harry Potter and the Order of the Phoenix, Harry attempts to use the Cruciatus Curse against Bellatrix Lestrange, in self-defense, but fails. Bellatrix taunts him for this failure, saying he has to "really mean it", that he has to really hate someone for that curse to be effective.
Harry Used The Imperius Curse Multiple Times During The Gringotts Heist. Death Eaters had a history of using Imperio to make innocent victims do their bidding. To keep the mission going as planned Harry Potter cast a second Imperius Curse on the Goblin before he could raise the alarm to stop them from robbing Gringotts
So, when Voldemort cast the cruciatus curse at Harry, the wand refuses to harm it's master and Harry is protected by his own sacrifice. That's why the curse is suddenly harmless and only succeed in levitating Harry.
Resistance. Resisting the Imperius Curse was possible, but required great strength of will and character. The fact that it could be resisted made it unique amongst the Unforgivable Curses, as it was the only curse that had a direct manner of defence.
The Killing Curse is one of the few spells which cannot be blocked. The only way to avoid it is to physically avoid getting hit by it. A known case of sacrificial protection stopping the effect of the Killing Curse is the protection put on Harry by his mother Lilly the night Voldemort killed his parents.
Weasley family patriarch Arthur was placed under the Imperius curse by Voldemort and his Death Eaters during the Dark Lord's rise to power, making him one of the few legitimate victims of the curse in a world where most of those who claimed they had been bewitched were just doing it to justify the actions they took
Two factors come into play with Harry's resistance to the Imperius curse. As Sammy Kumar's answer points out, Harry is naturally resistant to authority. His life experiences have made him distrustful of blind obedience. The second factor is the strength of the curse.
The pound is the actual unit of measurement, while “lbs.”, which stands for libra, is the common abbreviation used in expressing pounds. The correct way of abbreviation in expressing singular or plural pounds is “lb.”
(The first person singular is I, the first person plural is we.) Example: “I lied,” Charles thought, “but maybe she will forgive me.” Notice that quotation marks and other punctuation are used as if the character had spoken aloud. You may also use italics without quotation marks for direct internal dialogue.
1) Use an en-dash with no spaces on either side of it. Example: 9–10 a.m. 2) Use the “from X to Y” format. Example: from 9 to 10 a.m.