Changes to U.S. immigration policies may be abstract for many people, but for one startup, it was a very real roadblock. Y Combinator CEO Michael Seibel said that two of the three founders of a company in the latest cohort couldn't get the necessary visa to attend this summer's program. (He declined to provide more details about the startup to protect the founders' privacy.) A growing problem: Immigration policies are incredibly consequential for Silicon Valley — many of its most successful entrepreneurs have been immigrants or children of immigrants. And it's a particular problem for Y Combinator, which has made huge efforts recently to recruit startups internationally for its accelerator. In this latest cohort, 28% of the companies were not from the U.S., representing 16 other countries from around the world. Rule delay: President Trump's recent decision to delay the Obama-era International Entrepreneur Rule, which would have made it easier for foreign startup founders to run their companies in the U.S., has been a particular disappointment for the tech industry. One possible response: Law firm Mayer Brown is currently exploring potentially challenging the delay. The firm has reached out to Y Combinator and the tech community to learn more about its impact on the industry though there's nothing concrete under way yet, Mayer Brown partner Paul Hughes tells Axios.