An Auckland intermediate teacher was cleared of indecent assault charges at the Auckland District Court in March.

The Criminal Bar Association has criticised police handling of indecent assault allegations against a teacher who was eventually acquitted after a trial.

The association president also warned that allegations were easy to make up but could have "catastrophic" consequences for anyone falsely accused.

A teacher with a 40-year career was acquitted after a six-day trial at Auckland District Court in which a student admitted in the witness stand they lied about parts of their accusations.

All three complainants however continued to claim they had been indecently assaulted.

The jury took less than an hour to return not guilty verdicts on all seven charges the teacher faced.

READ MORE: Auckland teacher acquitted of sex charges against students

Criminal Bar Association president Len Andersen said: "Defence lawyers have expressed concern that the normal rule of investigation of offences does not seem to apply where allegations are of a sexual nature and, on the contrary, the complainant's accounts are not challenged and there seems to be a widespread assumption that such complainants are always telling the truth with little or no further investigation required."

He said while it was appropriate for any victim to be supported, there was no excuse for failing to carry out a proper investigation to determine whether there was substance to any allegation that could result in a prosecution.

"Where there is a child making the allegation, child witness interviewers facilitate the giving of statements on video and it is not their role to challenge the child or his or her recollection.

"This emphasises the importance of the police carrying out a proper investigation including a proper examination by the police of the motives and accounts of complainants instead of uncritically accepting their word that a sexual assault has occurred where the assault is denied by the defendant," Andersen said.

Andersen said: "Sexual abuse allegations are easily made and the effects of an allegation are catastrophic on the person who is accused whatever the final verdict."

He said it was "no answer" to say the system worked for the charged teacher because he was found not guilty.

"The falsely charged teacher's year from hell is a normal experience that any person would face who was charged with a sexual offence. If he or she is successful in obtaining bail then the bail terms are likely to significantly affect his or her life and may even prevent employment," Andersen said.

Police have not responded to this statement by the Criminal Bar Association but Detective Senior Sergeant Geoff Barber, responding to questions after the teacher's trial, said it was disappointing when members of the public became victims of untruthful accusations.

"It is important that police take allegations of indecent assault against any person seriously, especially those involving children.

"While we can't go into the specifics of this investigation, police are obligated to act on the information presented to us at the time a complaint is made and based on the information available, police took the appropriate action," Barber said.

The Crown case against the teacher was that he inappropriately touched three girls in his class, each aged 11 years. "The defendant stroked the students' hair in an indecent manner, swiped his hand over the chest area of two of the victims and grabbed the breasts of another victim," the court was told.

The teacher said that on March 23, 2017 he lost his temper in class after students began painting their hands and arms black. He swore at the students, and there was a tense standoff in the classroom.

His lawyer Marc Corlett QC claimed students decided to get the teacher fired because of that incident.

During the trial Corlett applied to have the case dismissed after the lies were admitted. But judge Robert Ronayne ruled there was still sufficient evidence for the case to go to the jury.

The teacher who was cleared said he had lost his confidence and his mental state had suffered over the last 12 months.

He said he would never teach again.