Because of lack of care
The doctrine is of Latin Origin
This legal maxim of Per Incuriam exemplifies that if any decision is given ignoring the provisions of any statute or any rule, then such decision or judgment will be considered as it was given per incuriam
To elaborate it can be said that any decision by any court was given mistakenly by ignoring or contradicting any rule or any provision of any statute or any authority, then such a decision will not have any type of binding force in it. any such judgment if is given per incuriam, then it will not be considered as a precedent for the lower courts and thus turns to be an exception for the Article 141 of the constitution. For example- In criminal cases, a decision made per incuriam will usually result in the conviction being overturned.
The maxim is properly and strictly applicable only for the rationale of a decision which is the point that determines the judgment and is binding in nature called the ratio decidendi and not a remark made during the course of the discussion having persuasive value called the obiter dicta part of the judgment.
K.H. Siraj v.High Court of Kerala, 2006
In this case the court observed that when a judgment is rendered by High Court decision in such a way that it is contrary to the Apex court rulings and thus not given recognition to the relevant decisions of the Supreme Court, then such judgment of High Court is per incuriam.
Punjab Land Development & Reclamation Corporation Ltd. v. Presiding Officer, Labour Court (Chandigarh), 1990
In this case the court held that if two decisions of the Supreme Court are conflicting or are not standing together, for which the court decided that Per Incuriam will actually rise there and it would not be a difficult issue as the Supreme Court of India could easily lay down the law afresh. One more important point which needs to be kept in mind is that non-recognition of any irrelevant rule cannot make the ratio of the decision per incuriam.
Buta Singh v. Union of India, 1994
Here the court discussed that if a two-judge bench ignores the decision of a 3-jugde bench or a higher bench, then such judgment will be said as per incuriam.
State of Assam v. Ripa Sarma, 2013
In this case, it was held that if any decision is ignorant of any earlier same decision of the same or different court or similar or larger benches, then it will not be pronounced as a precedent and will be said to be per incuriam.