if a house deed is signed over to three brothers is it legal for one to make a decision that the others are not in agreement with?

It probably depends on exactly what decision you are referring to, but in general, when property is co-owned without a governing partnership agreement, each owner has a right to deal with the property and a duty to account to the others, within limits.  There are requirements that co-owners contribute to maintenance and preservation of property.  But additional development might be restricted.  One "ultimate" remedy in the event of disagreement is a partition action which is results in a court order to sell the property and have proceeds split. There are usually additional details which make it not so cut and dried.  Is one owner seeking restitution for advanced expenses?  Or fees for managing the property?  Or leasing out the property on lower than market terms?  Or using it without paying rent to the others?