Barely a huge strain. As stated in the article, illegal immirants can not collect Social Security. Our jail and legal system is overflowing with all types of people, and illegal immigrants are only a small fraction of who is in the prison system:
Article from 2007 in the NY Times:
"In 2000, 27 percent of the inmates in federal prisons were noncitizens. Some of these noncitizens were illegal immigrants, and some were in this country legally. In 2001, this percentage dropped to 24 percent, and it continued dropping over the next four years, falling to 20 percent in 2005. "
“Over all — combining federal and state prisons — 6.4 percent of the nation’s prisoners were noncitizens in 2005. This is down from 6.8 percent in 2000.”