A motion to quash is a request to a court

Court

A court is a form of tribunal, often a governmental institution, with the authority to adjudicate legal disputes between parties and carry out the administration of justice in civil, criminal, and administrative matters in accordance with the rule of law...

 to render a previous decision of that court or a lower judicial body null or invalid. Such a motion isn’t always motivated by legal interests in vigorous pursuit of a case, but can arise out of mistakes made by any lawyer

Lawyer

A lawyer, according to Black's Law Dictionary, is "a person learned in the law; as an attorney, counsel or solicitor; a person who is practicing law." Law is the system of rules of conduct established by the sovereign government of a society to correct wrongs, maintain the stability of political...

 in a court proceeding. It may also be a lawyer’s decision to file a motion to quash if a mistake has been on the part of a court, or if an attorney

Lawyer

A lawyer, according to Black's Law Dictionary, is "a person learned in the law; as an attorney, counsel or solicitor; a person who is practicing law." Law is the system of rules of conduct established by the sovereign government of a society to correct wrongs, maintain the stability of political...

 believes that the issuance of some court document like a subpoena

Subpoena

A subpoena is a writ by a government agency, most often a court, that has authority to compel testimony by a witness or production of evidence under a penalty for failure. There are two common types of subpoena:...

was not done in a legal manner.