Americans and their political leaders have long resisted the idea of a national ID card. But after the Sept. 11, 2001, terrorist attacks, finding out who was in the country illegally took on new urgency. Two years ago, Congress passed a law to toughen standards for issuing driver's licenses — the main form of national identification. But practical problems and philosophical objections are dogging the Real ID Act. Seven state legislatures have already voted against putting it into effect in its present form, and 25 others are considering opposition. Critics argue Real ID licenses will create red-tape nightmares for millions of citizens — without making them safer. Proponents say the new law is needed because in some states current license standards have weaknesses terrorists can exploit. Meanwhile, another debate is under way on whether to raise standards for issuing Social Security cards.