There are several types of "hard-law".
"Center of the Universe"
She believes that her son should first think about it and always be "somewhere close" to go to her shop, to make repairs, to carry it to the garden, etc. Every day she would cook it "employ" and if he refuses, she immediately "sick" that he felt a sense of guilt and put all his affairs. In fact, in-law wants to be the center of attention. You can try to "switch" it on any hobbies or even on the right man, if in-law alone. In this case, it's still worth to explain that her son will help, but not to the detriment of his family.
"Hostile"
She tells you about bad things behind your back. Often it takes a little bit of truth and all the alters, changing the facts in their favor. If gossip reach you, and you ask the question directly in-law, she would deny everything. However, she complains to you son. She wants to get you divorced. Communicate with it as little as possible. If you have to contact, short, politely and diplomatically, considering every word. In a pinch, you can record the conversation on tape and then let's listen to the spouse.
"Assistant"
This law does not recognize personal space and is always ready to break into the room without knocking. You and your husband for her - still small children. She believes that you should bring up. Sometimes she pampers you, trying to manipulate her husband and with the help of your gifts and money (by the way, then they can be the same and reproach). This woman wants to do to control everything that happens in your family. Hints she does not want to understand, so with her husband better directly tell her that you do not like, and try to limit it to "omniscience."
"Rival"
She did not scold, not name-calling, not gossip, but critics, and very often. She knows better than you. Such in-law can defiantly teach you "how to" (mopping the floor, cook soup, walk with the child, etc.), or simply as indicative sad about the fact that you do not understand, and her son was not so lucky. "Rival" considers himself an ideal wife and mother. Therefore, it is - the best woman for her son. When the mother-in-asserting itself at your expense, quietly settle with her, not letting the conflict evolved.