The practice statement can only be used by the HOUSE OF LORDS, it is used to avoid having to follow their own precedent, this is the only court allowed to do this.
1.use not common
2. changes in precedent causes problems retrospectively
3.judges interpretations of the law should not be overruled
4.the practice statement should not be used if it easier for parliament to change the law
5.if a judge disagrees with a previous interpretation it should not be overruled