Can I petition to get custody of my brother due to drugs in the house he lives in under NY custody laws

I take it you are an adult sibbling. In that case, you can petition for custody of your brother. The court will look to the best interest of the child. The pot smoking in the home is one factor the court will lconsider in the decision. Your brother's willingness to live with you is another factor, whether you have a good relationship with him, whether he is emotionally attached to you, whether you can be a good provider for him emotionally, your financial ability to provide for him, whether you can provide a stable home for him and many other possible factors.

Please note you are leaving your mother open to the filing of a neglect petition if the state child protective serv ices gets involved. They can get involved because someone made a complaint or when a custody petiition is filed. The court typically orders an investigation of the respective homes of the parties seeking custody. Pot smoking will not be looked upon well in either case. Where a home is investigated for purposes of a custody petition and drugs and other issues are discovered the court itself can order child protective services to file a neglect case if appropriate.

where a neglect case is filed all minor minor children residing in the home maybe considered at risk, and therefore, subject to removal from the home.

You may need a lawyer to assist you in the process.