The 24-year-old starlet could wind up back behind bars if she is found to have violated her probation.
Fox had threatened Lohan with 30 days in jail for each probation violation. He will decide whether to send her back to jail or back into drug treatment.
"Judge Fox is the type of judge who is fair and decent, but I expect she'll have to go back to jail for up to 30 days," said Dana Cole, ABC News legal analyst.
Lohan reportedly failed two recent court-ordered tests. One showed the presence of cocaine in her system and the other allegedly tested positive for amphetamines.
Lohan admitted on her Twitter page last week that she failed a drug and alcohol screening.
"Regrettably, I did in fact fail my most recent drug test and if I am asked, I am prepared to appear before judge Fox next week as a result," Lohan wrote.
Cole said it's unlikely Fox will send Lohan back to rehab instead of jail.
"He's probably going to focus more on punishment issues," Cole said. "Additionally, he might try to put on some electronic monitoring so that she doesn't go out to clubs at night."
In August, the actress served 13 days of a 90-day jail sentence for violating the terms of her probation in a 2007 drug case. She entered a rehab program shortly after her release.
However, her stint in rehab was also curtailed after Fox ordered Lohan's released from the program after she served only 23 days of a three-month requirement at /*Ronald Reagan UCLA Medical Center*/.
In another Lohan development, the actress has withdrawn her $100 million lawsuit against E-Trade.
Lohan had claimed she was the implied target of jokes about a "milkoholic" baby named Lindsay in the financial services' ad that ran during the Super Bowl this year.
E-Trade called Lohan's claims meritless and noted that Lohan isn't the world's only Lindsay.
The Associated Press contributed to this report.
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