Until last week, USCIS held Adjustment of Status (AOS) applications in abeyance until three security clearances had been fully completed. The three clearances include: (1) FBI fingerprint check; (2) IBIS (or TECS) multiple governmental database check; and (3) FBI name check. Of these three, the FBI name check was the most problematic and, for some AOS applicants, the most time consuming.
On February 4, 2008 USCIS issued a policy memorandum in which USCIS directed that AOS applications be approved if (a) "a definitive FBI fingerprint check and the IBIS check" have been obtained and resolved, (b) "the FBI name check request has been pending for more than 180 days," and (c) the AOS "application is otherwise approvable." This represents a change over past practice in which USCIS would not approve an AOS application until the FBI name check had been fully resolved. Because some FBI name checks could take years to be resolved, some AOS applications remained pending for what seemed like an indefinite length of time.
In conclusion, for an otherwise approvable AOS application to be granted, a definitive FBI fingerprint check and the IBIS check must have been obtained and resolved and the FBI name check must have been pending for 180 days. After these security clearance steps have been completed, USCIS must approve "otherwise approvable" AOS applications. The USCIS policy memo can be viewed here.