Q: Can I make business decisions affecting the partnership without consulting my partner?
A: If your partner is readily available, you should consult him on any new decision (Aruch Hashulchan, C.M. 176:29).
If the partner is not available, you should act and make decisions according to the terms of the partnership agreement. In the absence of a specific agreement, you should conform to the common practice of that trade and not make decisions against the common practice without consulting the other party. If you did, and the decision resulted in a loss, you are solely liable (C.M. 176:10).
If a particular issue arose a number of times, and your partner agreed to deviate from the common practice without specifying that it was on a one-time basis, you may continue doing so without consulting (Mishmeres Shalom 176:1).
Verbal agreements at the beginning of the partnership are binding; afterwards, verbal agreements against the common practice without a kinyan are questionable (Rema 176:3; Mishpat Shalom 176:1).