House Democrats are calling for investigations into two temporary immigration courts that opened along the southern border last month where migrants who have been waiting in Mexico are fighting to obtain asylum in the US, according to a letter sent Thursday.

Laura Lynch and Leidy Perez-Davis, attorneys with the American Immigration Lawyers Association who visited the port courts shortly after they opened in September, said they and other lawyers from the National Immigrant Justice Center, Amnesty International, and the Women’s Refugee Commission were barred from observing proceedings in the courts absent a document showing that they were representing one of the migrants on site.