The six-year-old was wearing only a small dressing gown and his underpants and was found to have multiple bruises. The 35-year-old mother, who cannot be named for legal reasons, claims the bruises were caused by the child play - fighting at school.
Burnley magistrates were told how two separate calls had been made to the police at 11.15pm and both people who made them were quite distressed.
Prosecutor Miss Parveen Akhtar told the court it seemed the mother and child had been locked out of their house in Burnley. Officers took the boy to the police car and tried to find out what was going on.
She continued: "The mother was quite evasive and couldn't say where they had been, how they got home or how they were locked out. She was clearly under the influence of drink at the time. She wasn't drunk as she could hold a conversation, but for safeguarding issues they removed the child from her. Once back at the police station, a full examination showed multiple bruises on him."
Miss Akhtar added: "I understand the child has now been taken away from the defendant." The mother had no previous convictions.
Mr Ben Leech, defending, described the case as "particularly sad." He said the child went into care after the incident in May and had not been returned to the defendant.
The solicitor said: "She has engaged well with a number of agencies and has voluntarily been in touch with Inspire (the drugs and alcohol treatment service). She has done all she could."
Mr Leech said: "In the foreseeable future, the child will remain in care and she will continue to have some level of supervised contact, but at this stage there is no timetable for the child to return to the defendant. The child wasn't placed for adoption and there does remain some end goal for the defendant to focus on."
The solicitor said the child did have bruises and the defendant had been into his school to say he had been coming home with bruises on his legs. She had been assured they were caused at playtime.
Mr Leech said: "This was very much an isolated incident. She has paid a very heavy price and will continue to do so for that." The solicitor said the defendant, who had mental health issues and was on benefits, wanted to get herself back in full-time employment.
Sentencing, the magistrates said the child had been in fear, had injuries and he was a vulnerable victim. The chairman, who told the mother she had taken steps to improve her behaviour, said: "A six-year-old child shouldn't have to have this sort of thing."
The defendant, from Burnley, admitted assault by beating. She was given a 12-month community order with a 20-day rehabilitation activity requirement and a four-week curfew between 7pm and 7am, seven days a week. The woman must pay £85 costs and an £85 victim surcharge.