Arguing against immigration policies that force foreign-born innovators to leave the United States, a new study to be released on Tuesday shows that foreign nationals played a role in more than three out of four patents at the nation’s top research universities.

Conducted by the Partnership for a New American Economy, a nonprofit group co-founded by Mayor Michael Bloomberg of New York, the study notes that nearly all the patents were in science, technology, engineering and math, the so-called STEM fields that are a crucial driver of job growth.

The report points out that while many of the world’s top foreign-born innovators are trained at United States universities, after graduation they face “daunting or insurmountable immigration hurdles that force them to leave and bring their talents elsewhere.”

The Partnership for a New American Economy released a paper in May saying that other nations were aggressively courting highly skilled citizens who had settled in the United States, urging them to return to their home countries. The partnership supports legislation that would make it easier for foreign-born STEM graduates and entrepreneurs to stay in the United States.

“Now that we know immigrants are behind more than three of every four patents from leading universities, the federal laws that send so many of them back to their home countries look even more patently wrong,” Mayor Bloomberg said in a statement.

But some worry that the partnership’s ideas for immigration reform would undermine similarly skilled American workers while failing to address broader problems with immigration policy.

“No one is asking what is in their best interest, the American worker,” said Eric Ruark, director of research for the Federal for American Immigration Reform, an advocacy group that is pushing for reduced immigration. “It’s what is best for the employers. What is best for the foreign workers. It’s not as if the foreign workers aren’t skilled. What’s being ignored is we already have a domestic work force that has the same skills.”

The most recent study seeks to quantify the potential costs of immigration policies by reviewing 1,469 patents from the 10 universities and university systems that had obtained the most in 2011. The schools include the University of California system, Stanford and the Massachusetts Institute of Technology.

Patents, the study maintains, are a gauge for a nation’s level of innovation and an important way for the United States to maintain an edge in STEM fields.

In one illustration of the issue, the study notes that nine out of 10 patents at the University of Illinois system in 2011 had at least one foreign-born inventor. Of those, 64 percent had a foreign inventor who was not yet a professor but rather a student, researcher or postdoctoral fellow, a group more likely to face immigration problems.

Some of the patents that were reviewed for the report have become business ventures. Wenyuan Shi, a professor at the University of California, Los Angeles, earned a patent for an ingredient in a lollipop he developed that works as a dental treatment for children. A native of China, Mr. Shi has created a company to commercialize his inventions.

But current immigration laws can make it difficult for foreign-born students to remain in the United States after graduation. And employers may be wary of hiring them because green cards, allowing for permanent residency status, are limited and the process of obtaining one is cumbersome and expensive.

Under the current system, foreign-born students are allowed to stay in the United States for 12 to 29 months after graduation, provided they find a job or internship in their field.

After that, more permanent visas are difficult to obtain, restricted by factors like country quotas. The study notes that China is entitled to the same number of visas as Iceland.

Dr. Ashlesh Murthy came to the United States from India in 2001 to pursue a master’s degree in molecular biology at the University of Texas at San Antonio. Working with his professors there, he developed a vaccine for the sexually transmitted disease chlamydia, which obtained patents in 2011 and 2012.

Nonetheless, Dr. Murthy had to negotiate a bureaucratic maze to remain in the United States, and at one point was stuck in India for an extra month because American officials in India doubted a previously approved visa.

Noting that university officials petitioned a congressman to intervene on his behalf, Dr. Murthy, said, “If I was not in a position where they really wanted me, I seriously doubt I would have gotten back.”

* By , NYT, June 25, 2012