Attending an impromptu meeting or organizing a last-minute vacation in the United States is currently no challenge for most Europeans.
Under the so-called visa waiver program, visitors from 38 countries, most in Europe, are allowed to enter the U.S. for up to 90 days without a formal visa as long as they are traveling on business, for leisure or in transit to Canada or Mexico.
But after last month's terrorist attacks in Paris, a proposal facing a vote Tuesday in the House would put new limits on the 30-year-old program, which brings nearly 20 million visitors to the U.S. each year. And that could mean fresh headaches for some travelers amid questions about the effectiveness of the changes.
The proposal would ban citizens from the 38 countries and islands -- including most of Europe and also Australia, New Zealand, Japan, South Korea, Taiwan, Singapore, Brunei and Chile -- from receiving the visa waiver if they report on a travel application that they have visited Syria, Iraq, Iran or Sudan since 2011.
The proposal before the House, whose language was hammered out in talks between lawmakers and the White House, potentially would affect only a small number of passengers. However, some observers fear putting more stringent controls in place could actually make the U.S. less, not more, safe.
"Strengthening visa waiver program requirements would greatly increase the workload for processing visas, which could potentially degrade the quality of all interviews," Brian Michael Jenkins, a senior advisor to the president of Rand Corp. and the author of "Will Terrorists Go Nuclear?" wrote in a recent column in Britain's Guardian newspaper.
He noted that only three people who have been involved in terrorism incidents entered the U.S. via the visa waiver program in the last 25 years, pressing the point that added checks are unlikely to have any real effect on the nation's overall security.
The Telegraph, another British newspaper, warned that the changes could cause "transport woes" for up to 5 million Britons who do not yet have a new "e-passport" with a biometric chip, which could become mandatory under some plans being discussed.
The changes before the House would also require countries in the program to share traveler information with the U.S. government.
Permission to enter the U.S. under the current system is obtained via a Web-based system called the Electronic System for Travel Authorization, or ESTA, which performs basic security checks and requires a minimal processing fee. An applicant is not required to attend an in-person interview or be fingerprinted unless their application is red-flagged because of security concerns.
The ESTA permission is generally valid for two years and multiple trips.
Some nations have been slow to comply with even the existing U.S. visa rules and could face being kicked out of the visa-waiver program altogether if they do not agree with changes to come.
More stringent security checks and visa restrictions were enforced after the Sept. 11 attacks, causing frustration for many European travelers and a decline in the numbers seeking entry into the U.S.
Travel industry representatives have raised concerns that the proposed change in rules could have a similar effect.
"The stakes are high," the U.S. Travel Assn. said in a statement. "Negative impacts on international travel behavior may be a trade-off that many members of Congress feel like they can live with today, but at the very least they need a clear picture of what those are versus any purported security benefit."
Boyle is a special correspondent.