In most states before the plaintiff can file a medical malpractice claim, he/she must obtain a written opinion from a physician or other healthcare professional licensed in the same specialty. The opinion must set forth the standard of care required, the care actually provided, why the care provided violated the standard of care, and how the alleged care damaged the plaintiff.
Retaining an expert is expensive, but it is not necessarily difficult. However, it is the expense that generally prevents most inmates from retaining an expert. If the inmate cannot retain an expert, he/she cannot file a medical malpractice claim.
There is no such requirement for a deliberate indifference claim. The deliberate indifference claim is a federal cause of action and only requires the inmate to allege in his complaint that you knew of his/her serious medical need and that you intentionally deliberately ignored the serious medical need.
For this very reason, inmates often file frivolous and unwarranted claims against correctional healthcare providers. It is not unusual for a correctional healthcare professional to have five or more deliberate indifference claims during a career.