I found this in Tijuana. Its a pedestrian billboard with a picture of an arm with a profesional suit on sticking out between a steel fence handshacking another arm with a white shirt. If you notice, the arm with the white shirt has a hand cuff on its wrist.

TRANSLATION IN BOLD
The title says: Dentro o fuera? , Inside or outside.
Subtitle: Trato Digno , Dignified treatment.

Body: No hay Diferencia, There is no Difference
En Esencia todos somos iguales y tenemos derecho a un trato digno sin importar la raza, color o posicion social.
In essence we are all equal and we have the right to a humane treatment regardless of race, color of social position.

The billboard is sponsored by Accion Social Empresarial (Business Social Action)

By the title and the image of the steel fence I gather that this billboard is demanding that the rights of illegal aliens in the U.S. be respected and this is just a subtle way of stirring up support.