A military law specialist is an individual that is knowledgeable about all military laws, as they differ from civilian laws. For example, military service members that are accused of a crime may face military court rather than civilian court and the consequences can differ greatly. In addition, actions which are legal under civilian law may be illegal under military law.
A military law specialist may for example handle cases in which an individual is accused of disobeying a direct order. An individual may have disagreed with the desires of a superior and therefor, did not follow orders. That type of case would require the services of a military law specialist, as those laws do not apply to civilians.
A military law specialist must be familiar with both civilian and military laws in order to effectively handle cases for military members.
Military laws has more information on military law specialists.