The Supreme Court has held that deportation is not punishment, but rather an administrative procedure whereby an illegal alien is returned to his homeland. The alien has not been deprived of life, liberty, or property, so many constitutional protections do not apply.
Most important to the discussion is the fact that most detainees facing deportation are dealing with administrative charges in a civil process, rather than criminal. Consequently they do not have a constitutional right to an attorney; such protections only apply to criminal law.
There have been proposals in Congress to criminalize immigration law, and such a change could effectively grant illegal aliens a constitutional right to an attorney. But because such a change would also make it easier for state and local police to enforce immigration law, most immigration attorneys and so-called "immigrant rights" groups are hostile to the idea of criminalizing illegal presence. By arguing for a right to an attorney while simultaneously working to keep immigration law a civil matter these advocates are trying to have it both ways.
American citizens regularly deal with important civil matters without representation. This might include child custody cases, foreclosures, evictions in tenant/landlord proceedings, and divorce proceedings, just to name a few examples. Immigration attorneys are basically arguing that an alien facing a return home is more deserving of representation than a U.S. citizen fighting eviction from his home. I suspect that position might strike many Americans as unfair. Illegal aliens shouldn't be guaranteed greater protections than citizens.
Immigration attorneys argue that representation is important because it increases the likelihood that an alien will be successful at staying in the United States. This may be true because it gives immigration attorneys an opportunity to use their creativity to expand the scope of asylum, something they are constantly doing. Such litigation surely would lengthen an alien's stay in detention. Paradoxically, the advocates argue that representation will actually shorten detention stays because wise attorneys will discourage many illegal aliens from fighting tough cases and direct them to simply return home. I haven't met any immigration attorneys who are looking for fewer clients, so this claim strikes me as dubious at best.
These attorneys also argue that a right to representation is necessary because some U.S. citizens might get caught in detention. Obviously this is a serious concern; fortunately, it is a rare occurrence. According to a recent TRAC report, which looked at 50 months of detention records, 834 of nearly a million people issued detainers were U.S. citizens (about 0.08 percent). Of that 834, exactly 110 had been convicted of a crime. The report isn't clear on whether the 834 citizens were actually detained after being issued a detainer and ICE did not provide information on the nature of the cases. ICE did recently release a new detainer form and it includes a toll-free number for those who claim to be U.S. citizens or, alternatively, victims of a crime (read: eligible for a U visa which provides legal status). I suspect that this helps to prevent U.S. citizens from ending up in detention, but certainly ICE should do everything in its power to stop such scenarios from unfolding. Considering how small the numbers are, it is a bit much to use these rare instances as justification for providing representation to every alien in detention.
Ultimately, the best way to limit detention and, as a result fewer instances of aliens lacking representation, is to have less illegal immigration. This would require secure borders, a working exit-tracking system so that we know if legal aliens leave when their visas expire, and an end to the magnets for illegal immigration such as illegal hiring practices and sanctuary policies. But the very groups concerned about a lack of representation are opposed to anything that would discourage illegal immigration in the first place. The detention they decry is the natural result of their open-border policies.
As a side note, it is important to remember that many detained aliens hold the keys to the detention center, figuratively speaking, meaning they can leave and return home at any time. Lengthy stays in detention are often the result of aliens choosing to stay in the system and fight for a right to stay in the United States. But again, this process could be shorter if fewer people had to be processed — something possible through a serious commitment to immigration enforcement.