Lindsay Lohan back in court - and facing jail - after `failing sobriety test`

The troubled actress is due to appear in a Los Angeles courtroom, accused of testing positive for booze last week.

If the results are accurate, Lohan will be guilty of violating her probation from a 2007 drink-driving case.

The judge in her DUI case, Elden Fox, instructed the Mean Girls star she must stay sober under the terms of her probation - and warned her she would find herself behind bars if she did not comply.

According to US reports, Lohan took two sobriety tests last week - one of which she passed and one of which she failed.

One of the tests was apparently conducted shortly after Lohan, who is currently under house arrest, threw a rooftop barbecue party at her home in Venice, California. In both tests she is understood to have tested negative for drugs.

Lohan, 24, is due to appear before Judge Stephanie Sautner this morning at LA's Airport Courthouse.

The LA County Probation Department will reportedly ask Judge Sautner to cancel the actress's house arrest and sentence her to jail.

Representatives from the District Attorney's office will apparently also be present to attempt to strengthen the case against Lohan.

Lohan began a 35-day house arrest term last month after being accused of stealing a $2,500 necklace from a jewellery store in Venice.

The Mean Girls star, who was on probation from her 2007 DUI conviction at the time, was originally sentenced to 120 days behind bars after pleading no contest to a misdemeanor charge.

But her punishment was reduced to 35 days of home confinement due to jail overcrowding. She was expected to be released at the end of this month.