Stare decisis.

Stare decisis  means to stand by things decided.  It  is a  latin maxim     expressing  the underline basis of  the doctrine  of precedent, i.e that  is necessary to abide by former  precedents when the same points arise again in litigation.  It  is principle of law by which precedents are authoritative  and binding  and must  be followed.

Note:  Ratio Decidendi-  is a latin maxim meaning  the reason for deciding  or  the  reason of a  judicial  decision.  It  is a  principle of law on which the  court  reaches it  is decision.  It  is a  ratio decidendi  of the case  that makes the decision  a  precedent for the future.