No person shall be involuntarily admitted to or confined as an involuntary patient at a designated psychiatric treatment or hospital, and no designated psychiatric treatment facility or hospital shall involuntarily admit or confine as an involuntary patient any person, unless such person is determined to be a person with a mental condition and found to be dangerous to self or dangerous to others in accordance with the procedures prescribed by this chapter, and unless the procedural requirements of this chapter are complied with. A person may not be admitted to or confined as an involuntary patient at a designated psychiatric treatment facility or hospital unless it is determined that such placement is the least restrictive intervention reasonably available and the person has declined voluntary treatment. No person shall be deemed “involuntarily committed” for any legal purpose until the court deems the person an “involuntarily committed” person at the conclusion of a probable cause hearing held pursuant to this chapter.