There generally are exceptions to any rule.
For example, if a dog jumps up on me, I'll say down, he does it again I will indeed knee him in the chest, 3rd time I really knee him hard so he flips on his back. One way or another he will get the a loud and clear message it is not acceptable to jump up on me.
Another example is with an Alpha dog. They can be very hard headed, and to establish that you are the boss and not him/her, sometimes you do need to use force with them.
But the above is not "beating" a dog. I recon what I consider a beating is when one repeatedly hits a dog, especially if more than several wacks are done. And not to anothers dog either. If excessive, call the police for animal cruelty charges. Neither man nor beast should be beaten IMO.
DT, the question of discipline for you is this, why is your dog at your inlaws? Maybe keep him at your house instead of bringing him along. If you are at your home and your BIL does it, then I say in no uncertain terms he is to be informed not to discipline your dog, but rather to inform you instead. If he continues--make it clear he is not welcomed in your home any longer if he continues such actions. Some things a Man needs to do to have self respect of ones basic core values and needs to say enough, despite family politics.
Also watch for "signs" from his wife if she is being beaten too. Generally if a person goes off on a animal to excessively beat it, they may also do the same to people too, and all too often of immediate family members.
I sincerely hope this is not the case, but cruelty to animals can sometimes lead to spousal/child abuse. :thumbsdown: Guys this goes for all of us, be it your neighbor, relative, etc.. often there are "signs" of abuse, be it animal or people, if you know what to look for. It is better to say "enough", before an animal is severely injured or a person ends up in the hospital or worse. It is a tough call to make, but often that is what distinguishes a man from a boy. There are ultimately only 2 you need to answer too in life. The man in the mirror and the Big Guy in the Sky. :yes: