International law is quite clear on the matter. According to the 1951 U.N. Convention Relating to the Status of Refugees, migrants who've crossed an international border to seek asylum should not be discriminated against, penalized or sent back to a place where they could be in danger. "If someone arrives in a country without authorization, really the only recourse they have to stay in that country is if they have a claim of persecution under the refugee convention," says Susan Fratzke, a policy analyst at the Migration Policy Institute in Washington, D.C. She adds as a caveat that they may also be allowed to stay under a few other circumstances, for example "if they fear return to their country for some other reason."