ON JANUARY 29 , Dr. Amin Shokrollahi was planning to do something he had done many times before: take a flight from his home in Switzerland to the United States. Shokrollahi, a dual German-Iranian citizen, is a renowned mathematician, computer scientist, and a professor at the prestigious École Polytechnique Fédérale in Lausanne. Once in the U.S., he was to deliver an address at the International Solid-State Circuits Conference (ISSC) in San Francisco.

The next business day, a concerned Shokrollahi went to the U.S. Embassy in the Swiss capital of Bern to try and speak with an American consular official. As a German passport holder, he had for years been entitled to the same rights of visa-free travel to the United States as his fellow citizens. After waiting three hours, he met with a consular official, who asked him questions about his personal background.

“I had planned this trip a long time ago, and was preparing to give a talk on low-energy-consumption technology at the ISSC conference,” Shokrollahi said. “It’s very prestigious to be invited, and I had scheduled several meetings in the expectation that I’d be flying into America soon. I had heard that there were potential legal changes coming in the United States so had checked the website before I left, but I still didn’t know if it would affect me personally.”

Days before his flight, however, when Shokrollahi checked the U.S. Customs and Border Protection’s online website to confirm that his visa application was still in order, he received an unpleasant surprise. Due to a recent change to the Visa Waiver Program that targets dual citizens of Iran, Sudan, Iraq, and Syria , his permission to visit the United States had been changed to “not authorized.” Weeks before, the U.S. Congress had passed the “Visa Waiver Program Improvement and Terrorist Travel Prevention Act,” a measure that effectively made European-Iranian dual citizens like Shokrollahi ineligible for visa-free travel to the United States.

“She asked me whether I was a dual citizen. I told her, ‘Yes I was born in Iran and have citizenship, although I left the country 36 years ago when I was a teenager,'” Shokrollahi said. The consular official proceeded to ask Shokrollahi how often he travels to visit family in Iran, whether he had ever served in the Iranian government or military (he hadn’t), as well as various other details about his career and personal life.

“At the end, she told me that because of my nationality and field of study, I was not eligible to travel to the United States under the normal visa guidelines and would have to wait six to eight weeks for additional processing,” he recalled. “I told her I was scheduled to fly out the next day. She said that wasn’t going to be possible.”

Under normal circumstances, citizens of European Union countries can receive authorization to travel to the United States through the U.S. Customs Electronic System for Travel Authorization (ESTA) website. After filling out a short questionnaire and paying a $14 fee, the process is usually completed within seconds. The authorization typically lasts up to two years, or until the applicant applies for a new passport.

A routine traveler to the U.S., Shokrollahi had gone through the ESTA process many times before without issue, most recently in August. On that visit, he had come to meet with clients, investors, and employees of his U.S.-based electronic engineering company.

In early December, when he again applied to renew his ESTA authorization, the system granted it without issue. However, that same month, Congress approved the tightening of the Visa Waiver Program. After the legal changes came into effect this January, Shokrollahi’s status on the ESTA website changed to “not authorized,” just days before he was scheduled to fly.

Suddenly, he found out that he wouldn’t be able to speak at the conference, or meet with investors and clients for his growing business.

“There are many accomplished Iranian-European dual citizens working for multinational corporations and universities who often need to travel urgently and without much prior planning, something which makes getting a U.S. visa a major impediment,” said Kayvon Afshari, communications director at the American Iranian Council. “As a result of the new visa waiver regulations, they can no longer freely travel to the United States like their fellow European citizens, something that can have real negative impacts on both economic activity and academic development.”

In the case of Shokrollahi, these losses may have been both tangible and significant. “I have five American employees in my business and had been planning to meet with investors to open a new office in Silicon Valley. On this trip alone, we were expecting to discuss millions of dollars in potential business,” he said. “But after having to cancel everything at the last moment, it suddenly feels a bit up in the air.”

Shokrollahi himself was once a permanent resident of the United States, where he lived for a decade while studying at University of California, Berkeley, and conducting post-doctoral work. Though he now resides in Europe, he still travels to the United States as often as five times per year to help run his business and to attend academic events. Now, kicked out of the Visa Waiver Program and unsure whether he will be able to obtain a multiple-entry visa, his American ambitions suddenly appear limited.

“The United States should decide what laws are most suitable for itself and it’s not for me to judge their propriety. But I must point out that these types of discriminatory measures are really impacting innocent people,” Shokrallahi said. “I have the same passport as my wife, who is a single-citizen German, and she has no problems. Why should it be any different for me? What did I do? I’ve been branded differently based on my ethnicity, and as a result, I do feel as though I am a second-class citizen.”