This question clearly goes to the very heart of the issues that are raised by this excellent play. On the one hand, we have the fact that the women clearly find a motive for Minnie's murder of her husband in the dead canary. However, at the same time, Mrs. Hale's knowledge of John Wright enables her to understand the kind of souless existence and hardships that Minnie would have experienced in her marriage to him. These two sides of the argument are expressed initially by the two women. It is Mrs. Peters who has to remind Mrs. Hale that murder is a terrible thing, but it is Mrs. Hale who fills Mrs. Peters in on the background of Minnie Wright before she married and the kind of man that John Wright was.
The question we need to really think about is, is murder ever justified? For Minnie, having suffered a kind of murder of her own life through her marriage, is it acceptable for her to kill when she is so badly treated over a period of years and years? On the one hand, life is presented as a precious object that should not be dismissed lightly. However, on the other hand, the way in which both women at the end conspire together to hide the canary from the menfolk indicates that they feel Minnie has been punished enough already in life without being accused of murder too.