Is Lennie's killing by George justified in Of Mice and Men?
In my opinion, Steinbeck wants us to believe that George is justified in killing Lennie and that he really has no other choice. In the 1930s, when the novel is set, there were no special education programs or federal disability laws. People were unlikely to have any understanding of the mentally challenged. In those days people like Lennie had very few alternatives and might have found themselves in a mental hospital if no one was available to care for them. Law enforcement would have been apathetic toward Lennie's disability. They would have locked him up and treated him very poorly if he had been apprehended after the accidental killing of Curley's wife.
Steinbeck foreshadows Lennie's death in chapter three when Carlson kills Candy's dog because the dog has become old and crippled. The dog was Candy's best friend, and he couldn't bring himself to put the dog out of its misery himself. He confesses to George that his lack of action was a mistake. He says,
“I ought to of shot that dog myself, George. I shouldn’t ought to of let no stranger shoot my dog.”
This must be on George's mind in chapter five when Candy shows him the dead body of Curley's wife. After asking Candy to wait before telling the other men about the girl, he sneaks into the bunkhouse and takes Carlson's Luger.
George may ultimately make up his mind after Slim implies that George must do something about Lennie. Slim says,
"An’ s’pose they lock him up an’ strap him down and put him in a cage. That ain’t no good, George.”
George realizes that Lennie wouldn't understand being locked up and he doesn't want his friend left at the mercy of Curley, who is angry not only about his wife, but more so because Lennie has crushed his hand. George does the only thing possible to save his friend. Slim affirms George's decision in the end of chapter six when he says,
“You hadda, George. I swear you hadda. Come on with me.”