The man, named as 41-year-old Tyrel Martin Marhanka, is thought to have hidden the dismantled scissors inside a magazine to get past a metal detecting door, Changhua district court said.
The court vowed to beef up its security control by adding two X-ray scanners when it moves to a new building.
There is not enough room for the scanners at its current facility, it said.
When the judge handed down a four-year prison sentence for smuggling poppy and marijuana seeds and for growing marijuana, Marhanka stabbed himself in the neck before bailiffs could stop him.
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"We deeply regret that Tyrel Martin Marhanka killed himself during the sentencing," the court said in a statement.
"He was cooperative during the investigation and the trial. His attitude was mild and he did not show any signs that he would commit suicide."
Marhanka was married to a Taiwanese woman with two children and had been living on the island for many years, according to the court.