I think that the title of "Legal Alien" in Mora's poem helps to point out the liminal quality of the modern immigrant. The vision that Mora gives is far from the assimilative melting pot vision in which individual identity melts away in a homogenized vision of being "American." In the modern construction of immigration, one lives at "the hyphen." The result of immigration becomes a liminal condition where one is forced to acknowledge a specific estrangement from the dominant culture as well as the indigenous one. It is in this light where I think that the title of "Legal Alien" holds much in way of relevance and thematic meaning in the poem.
Mora's poem does not present immigration in a simplistic or easy manner. Rather, it is a complex condition of being. One is legal, in terms of jurisprudence. However, there is a social condition that cannot be bridged through papers and proper documentation. Mora suggests this condition in the line that the modern immigrant is "sliding back and forth/ between the fringes of both worlds." They are "Bi-lingual, Bi-cultural," yet without a home because of the reality "of being pre-judged /Bi-laterally." There is no other way to describe them but being a "legal alien." They have made their way into a country, but are foreign to the cultures within it. In being alienated and estranged from a culture that fully accepts them, one where they do not have to don the mask of smiling contentment, the condition of being a "legal alien" carries with it much in way of symbolic and literal struggle in consciousness. It is here in which the title is significant to the overall meaning and thematic relevance to the poem.