My sis in law is a controlling parent, is this right of her?

[Pop]

I just don't understand her, I mean she controls everything about her daugther. Like if I wanted to take my niece to the park or something, she'll usually say no. She never lets me do anything with her, it's like she doesn't trust me at all. Than I ask my brother who's the dad if I can do something with my niece, and he'll usually say yes to me, but than my sis in law comes over and says no, and like we get in this big fight. I'm like telling her that my brother said I can do it, and she's all like no I don't care, you're not taking her anywhere. She acts like she can just overrule my brother like that, it's so pissing me off. I mean do moms usually have more control over kids than the dad or something? One time I took my niece to the mall without my sis in law's permission, but I had my brother's permission, and guess what she did, she called me right, asked where I was, and she actually drove to the mall and took my niece away from me. How insane is that? I don't like her, my brother lets me do what I want but my sis in law never does. She's too controlling, what do you think can be done about this? If she doesn't change, than I want my brother to divorce her.