Canon law - vows, acquired rights meaning problem I have a problem with meaning of dispensation from vow restrictions (canon law 1196). I have read that dispensation must not injured rights acquired by others (i have read that it's regards lawfully rights). Question is: I vowed only to God (none hear that) to won't do action to my brother which is also a lawfully right acquired by him before my vow to God. And now I don't know if dispensation from my vow injured his acquired rights or not? 
Problem is in meaning acquired rights - acquired at all (in lifetime) or only by vow? 
Please respond and sorry for my language. Regards.
Acquired rights are refered to several times in the Canon Law. The concept of acquired rights is common in many legal systems, including International Law.

An acquired right differs from a natural right or a general legal right. A person may have an acquired right because of something that has happened to him, or more usually something he has done. It is not a right everybody has.

A country might decide nobody can be a doctor unless he can pass an exam in Portuguese. But people who are already doctors have an acquired right to continue being doctors. Also medical students who have begun training may  have an acquired right to continue, and to qualify as doctors, without learning Portuguese.

An acquired right is not absolute. The country could make a law that any doctor who does not pass a Portugese exam by a certain date is no longer a doctor.    

Another example is a man who owns a field and asks for Planning Permission to put up a tall fence round it. Permission may be granted on condition it does not injure the acquired rights of another person. Somebody may have used the field as a path for so long that he has acquired a right to continue using it. Or somebody may have paid for the right to keep sheep in it. The Planning Authority does not know what acquired rights there may be. But it could grant permission provided it does not injure any rights there may be.

Alternatively permsssion could be granted despite certain rights, thus overriding the rights, either specific rights stated, or any rights at all, known and unknown. 

In the case of Dispensation from a Vow the Dispensation must not injure the acquired rights of another person. The rights are   those acquired by any means up to the date of the dispensation.

A private vow, known to a third person who stands to benefit from it, could give rise to a right. For example, a vow to fund somebody's education.  

A private vow, known only to the person making the vow and to God, cannot of itself confer a legal right on anybody. The dispensation from the vow cannot therefore alter the rights of another party.   

If OP's brother already had a legal right before the vow and he still retains that right now,then neither the vow nor the dispensation has had any affect on his rights.

There may be other moral issues though, which is why if at all possible, it may be best to seek the advice of a priest who will seek to understand the full picture of the situation and advise accordingly.