The Polish military will be allowed to shoot down hijacked aircraft as a last resort, according to a decree adopted by the government.
Poland has been spared plane hijacks in recent years
The decision will have to be made by the country's defence minister or the air force commander after attempts to land rogue planes have failed.
Defence Minister Jerzy Szmajdzinski said such a decision would be the most difficult one of his life.
Poland is a key ally in the US-led anti-terror coalition.
It has been stepping up anti-terror measures ever since it deployed the third biggest contingent in Iraq after the US and Britain.
A similar shoot-down law has caused controversy in neighbouring Germany, where President Horst Koehler, who signed the bill, said that it could be unconstitutional. He has urged a review by the high court.
A number of other countries adopted such laws following the 11 September 2001 attacks in the US.