There’s been some confusion here. For Oregon license reinstatement after a DUII conviction, you must first wait out the suspension period, and then:
(a) file a SR-22 insurance certificate with DMV for 3 years, ORS 806.075; and
(b) install an Ignition Interlock Device (IID) for 1 year for a first conviction; 2 years for second, ORS 813.602(1); 5 years for third or subsequent, ORS 813.602(2).
Some folks were confused by 2011′s House Bill 3075, which added an IID requirement for DUII Diversion as of January 1, 2012. However, the Bill did not change the already existing IID requirement for people convicted of DUII, as opposed to those entering Diversion (I think the confusion stems from the fact that newspaper coverage at the time covered the Bill as introduced, which did extend the time for IIDs for DUII convictees to be 2 years, across the board. The Bill was not passed in that form.).
Even if the law had changed for the worse between, say, the time of conviction and the time a person was ready for reinstatement, Mannelin v. DMV, 176 Or App 9 (2001), says that the more onerous current statute would apply. Mannelin rejected expertly-argued ex post facto, double jeopardy, and bill of attainder arguments. In Oregon, the law at the time of reinstatement is what applies.
Finally, third DUII convictions come with a Lifetime License Revocation. There is only one, very limited, escape valve from that lifetime sentence, and it deserves it’s own separate blog post.