A Berkshire woman has started a petition after being refused a blue badge to help her severely autistic son.
Carolyn Fox, 48, from Tilehurst, was turned down by Reading Borough Council because son Ryan, 18, is not physically disabled.
It said it was following Department for Transport (DfT) guidelines.
But Alok Sharma, Conservative MP for Reading West, said Mrs Fox "absolutely needs and deserves" the badge.
Mrs Fox believes that requests for the badges, which give access to disabled car park spaces, should be looked at by the council on a case by case basis.
She said: "We had an incident where I had to park right at the top of the car park because I didn't have a badge and when we came out of the supermarket he started to go off on one.
"By the time I got him to the car, which was a couple of minutes, he completely lost it and headbutted the windscreen and smashed it to pieces.
"I can see it coming so if I can get him back to the car quickly where I've got supplies and drinks to calm him down he hopefully wouldn't get to the meltdown stage."
The petition points to the fact that Ryan is 18 stone, and when he throws himself to the floor "his 6 stone mum has no hope".
The DfT guidelines state medical conditions such as autism do not qualify someone for a badge unless "they are unable to walk or have very considerable difficulty in walking".
But it adds that local authorities are responsible for deciding whether someone is eligible.
Mr Sharma said: "What Carolyn and her family are going through is very, very difficult and we should be trying to help them, but they won't be the only family facing such difficulties."
According to the National Autistic Society "children with autism may be able to handle an activity such as walking to the shops one day and not be able to do it the next because of factors such as anxiety, fear or stress.
"If it can be demonstrated that these incidents happen on a frequent basis and are a direct result of their disability then you could argue they satisfy the criterion."