The number of Miami-Dade students taken by school police from campus for an involuntary psychiatric exam has almost exactly doubled in the past five years, according to the district’s records.

At least 646 times this year — that’s an average of more than thee times every school day — Miami-Dade school police have handcuffed a student, put him or her in the back of a patrol car and driven to a mental health facility under the rules in Florida’s mental health law, the Baker Act.

The rise has come at a time when school crime statistics and juvenile arrests are down markedly.

Critics, including some inside the district, say the schools may be overusing the Baker Act, which allows individuals to be held for evaluation up to 72 hours. Some critics say it might be a deliberate effort to tamp down campus crime statistics.

District administrators say the numbers are reflection of schoolteachers, counselors and police becoming more alert and sensitive to the emotional problems of students at a time when kids face more pressure than ever.

“Over the past two years, we have trained all counseling professionals, school administrators and school police officers on the early warning signs of emotional at-risk behaviors,” said John Schuster, the district’s communications chief, in a statement. “More importantly, we have imbued all of our employees with a sacred responsibility to seek immediate assistance for any student exhibiting signs of suicide or homicidal ideation, plan or threat.”

District officials also point out that the use of the Baker Act in society at large has risen significantly.

Nonetheless, Miami-Dade school officials are investigating concerns about the Baker Act’s possible overuse. Schools Police Chief Charles Hurley has been temporarily reassigned to desk duty pending the outcome of the probe, which involves separate allegations of sexual harassment.

At least one longtime and well-respected school psychologist has voiced reservations about the practice of Baker Acting children.

Frank Zenere wrote an internal complaint this month to a high-ranking school official saying his boss — Suzy Milano-Berrios, who runs the department of mental health and crisis management services and has been the subject of a slew of recent complaints from her own employees — “coerced us to persuade school officials and school police to Baker Act students, even at times when it was not warranted.”

Similar concern has reached Habsi Kaba, who coordinates Miami-Dade County’s Crisis Intervention Team, or CIT, program. She trains officers in mental health issues and the Baker Act and serves as their liaison.

“It has been brought to my attention that there has been some pressure to initiate involuntary exams,” Kaba said.

In 2006, Miami-Dade schools police started participating in the 40-hour long CIT training, but stopped last summer, Kaba said. In the training she teaches officers the legal criteria — such as concerns that a student is likely to hurt himself or others — to initiate an involuntary exam under the Baker Act. “That’s what the officer has to follow,” she said. “If someone is pressuring them to initiate an involuntary psychiatric exam more frequently, then it’s not in their control anymore.”