This article provides a useful summary of recent Civil Guard disciplinary controversies. The professional association believes Guardia personnel should not be subject to the Military Criminal Code. Excerpt (modified Google Translate translation):
There are precedents for convictions affirmed by the Military Chamber of the Supreme Court in this regard. Thus, last March the court upheld a nine-month sentence awarded to a civil guard of the Valencia Command for the crime of "insulting a superior," to whom he referred in a "high tone of voice" and in a "little respectful" way. The events date back to May 28, 2016 when the civil guard reprimanded a chief patrol corporal for leaving an area with sewage where a possible ecological crime could have occurred.
This agent used a "high tone of voice" and a "disrespectful manner," says the decision. He told the corporal he was a "damn inept" or "useless shit."
In 2015, another civil guard entered the Madrid prison of Alcalá Meco to serve four months for the same crime. The Supreme Court had affirmed the sentence imposed for shouting at his boss: "[homophobic term omitted], you have no eggs [slang for balls], what you have to say you say to my face."
The Supreme Court considered that the phrase was "significantly offensive as injurious, insulting and unworthy" and "therefore constituted a crime." The decision also emphasized that "the crime of insulting a superior, in addition to protecting the personal dignity of the offended, protects, especially, military discipline, which governs members of the Civil Guard as military personnel."