Pocket Veto

Pocket Veto
Pocket Veto is usually a legislative tool that the United States’ president can use to discard a bill even without having to reject it formally. The United States Constitution demands that a president returns a vetoed bill to the assembly within ten days of getting it back for reconsideration and probable override by the Congress, minus Sundays. In case the president fails to veto the bill, it automatically becomes law.
However, if the assembly defers before the ten days are over, and the president does not sign the bill, it does not qualify to be a law. The bill therefore dies, and the president still achieves his wish of a veto without having to veto the bill. Additionally, the bill never returns to the assembly for reconsideration, and thus the Congress cannot overrule the pocket veto.
In 1812, James Madison first used the pocket veto and had since then been used by presidents. In fact, most times, Congress has attempted to twist the law in situations that a pocket veto is applicable, for instance, during the Congress break that happens between the first and second sessions. Congress has also made efforts to firmly define congressional postponement, stating that a pocket veto occurring through inter-session delay is allowed, but one happening through intra-session deferment is not.
Furthermore, the Supreme Court has handled many cases seeking to reverse a pocket veto. The rulings in these cases have resulted in some slight patterns arising in the application of pocket veto.

However, the proper use of the pocket veto, and the situations when a president can lawfully apply it have remained murky even to date. Presidents must, therefore, be keen afore using the pocket veto to avoid the challenge by the Supreme Court to a pocket veto as it could have negative implications on the ability of a president to apply pocket veto.
References
Kennedy, E. M. (1977). Congress, the president, and the pocket veto. Virginia Law Review, 355-382.
(Kennedy, 1977)