Lindsay Lohan's SCRAM device signaled that the actress had alcohol in her system; the device on her ankle did not go off accidentally.
Judge Marsha Revel met with a prosecutor and an attorney for the star after reviewing the SCRAM report.
"Lindsay had alcohol in her system," Radar Online quotes a source.
"It's not an accident. The bracelet didn't go off by itself. She had ingested alcohol.
"There was absolutely proof of alcohol in her system and that's why the judge did what she did."
Lohan had earlier this week taken to Twitter to reject the suggestion she had been drinking, posting: "My scram wasn't set off – It's physically impossible considering I've nothing for it to go off."
Shawn Chapman Holley, the 23-year-old's attorney, has confirmed the report, stating: "This morning Judge Revel was advised by a SCRAM representative that Ms Lohan's court-ordered alcohol bracelet had indicated the presence of a small amount of alcohol on Sunday night. Having just received the report, I am not in a position to speak to its accuracy or validity, however Ms Lohan maintains that she has been in complete compliance with all of the terms of her probation and her bail. Bail has again been posted in Ms Lohan's case and she will continue to comply with all of Judge Revel's orders."