In an editorial, Nature calls out principal investigators who are using their influence over visas to create working environments that take advantage of foreign postdocs.
A recent study appearing in Research Policy found that a major, unexpected issue facing postdocs in the US, is what it called "socially irresponsible behavior" by PIs, which included such visa issues. Arizona State University's Christopher Hayter and California State University–Los Angeles' Marla Parker interviewed 97 postdocs and 35 others, including PIs and university administrators, to explore what factors may prevent postdoc from pursuing careers in academia. About half the postdocs were from the life sciences. Postdocs told Hayter and Parker that PIs would threaten visas — J1 and H1B visas in the US are issued for particular positions and renewed yearly by universities, which gives PIs control over their renewal — if they did not double their hours in the lab or work for less than the minimum salary.
This, Nature says, is exploitation and is unacceptable, and says that it "must stop."
The paper authors note that their study was small and qualitative, and therefore might not be widely generalizable. "Let's hope not," Nature writes. "Everyone should agree with the postdoc who told the interviewers: '[I] realized that students can really be taken advantage of and this left a bad taste in [my] mouth with academia.'"