Here's more on the 1986 amnesty scheme and how the current amnesty schemes will end up doing the same things. A snippet:

It is clear the 1986 immigration "reform" legislation was an abject failure. It did not stem the flow of illegal aliens, since we now have many more times the number of illegal aliens in the US than we did before 1986. The legalization process created a huge venue for fraud. Legalization included a Special Agricultural Worker (SAW) provision that allowed illegal aliens who could establish they worked in certain types of agriculture during certain time periods to gain legalized status. This opened the door to massive fraud.

And, as detailed in Chapter 3 of the 9/11 Commission Staff Report, "Mahmoud Abouhalima, involved in both the World Trade Center and landmarks plots, received temporary residence under the Seasonal Agricultural Workers (SAW) program".

The legalization adjudication system, counting on the "expert" numbers in the few hundred thousands, was soon completely overwhelmed. Temporary adjudicators were quickly hired on contract and given little training. Documentary evidence provided by the alien applicants was given little review and analysis and sometimes none. When aliens had no such supporting documentation, they were allowed to simply present a sworn affidavit attesting to their work background, along with an affidavit of another "witness" and these affidavits were accepted as the totality of their supporting evidence (what, an illegal alien lie to get an immigration benefit?). As noted, fraud was rampant and there were few investigative resources to pursue it.