I'm 150 words, how is the theme of social injustice developed at the end of The Circuit?

Francisco is ready to recite his memorized portion of the Declaration of Independence and Border Patrol show up to take him away. Seriously-they just show up at his classroom and that's it, Francisco knows what's going to happen (he's heading back to Mexico), and he's not fighting it. Francisco is about to read one of the most important documents in American history (one that talks about freedom, rights, liberties etc.), and he is just taken away without a say in it; this contrasts the 'rights' that illegal immigrants compared to U. S. citizens, because they aren't always treated humanely.