The judge just threw the book at Michael Lohan's baby mama Kate Major -- sentencing her to 8 months in jail for being a really drunk scofflaw.
Major was hauled off to lockup in Palm Beach Monday after pleading guilty. The DUI conviction triggered a probation violation, stemming from Major's 2012 battery case ... when she allegedly attacked a police officer in Boca Raton.
As a result, the judge revoked Major's probation and sentenced her to 8 months in jail ... with 70 days credit for time served. Major will begin serving the balance of her jail time immediately.
As we reported, Major was arrested for DUI in March ... the arrest video is legendary.