In Of Mice and Men, Lennie is disenfranchised. When he accidentally kills Curley's wife, Lennie has no rights when it comes to his side of the story. Lennie would never harm anyone intentionally. He is a gentle soul with a big heart. Lennie is mentally challenged. George is his only friend. Even though George gets frustrated with Lennie, he is only concerned with Lennie's well being. George realizes that Lennie will hang for killing Curley's wife. George realizes that Lennie will not get a fair trial.
Lennie is not capable of making good decisions. He panics. His anxiety gets the best of him. When Curley's wife screams and tries to get away, Lennie is only trying to quiet her. He is too strong for his own good. He accidentally breaks her neck:
With one hand over her face and the other at the back of her head, he shakes her. When he lays her on the ground, she is still and quiet. He has broken her neck. He realizes that she is dead and that he has done another bad thing.
Now, Lennie is as good as dead. Curley will have no mercy on him. Even though Lennie is mentally challenged, Curley will see that he hangs. Truly, Lennie will not have any rights to a fair trial. George realizes that Lennie will suffer by hanging. George would rather shoot Lennie himself than to see him treated as a criminal.