After Boston suspects ID 'd , politicians start blaming immigration system . Alden : Perfect screening is impossible and would n't have prevented the bombings . Both could well have become caught up in the extremism that has roiled too much of the Islamic world and caused others to carry out horrifying , senseless attacks against the innocent . Comment: We need immigration reform , but must be realistic about what it can and ca n't do .
After Boston suspects ID 'd , politicians start blaming immigration system . Alden : Perfect screening is impossible and would n't have prevented the bombings . Comment: We need immigration reform , but must be realistic about what it can and ca n't do .