An ex-vet accused of stalking his MP said white powder found on an envelope he sent to her was toothpaste and offered to taste it in court.
Maurice Kirk, 76, denies harassing Taunton Deane Conservative MP Rebecca Pow over a year-long period from 2019.
He is accused of being abusive towards her staff and making an unannounced visit to her Somerset home to hand deliver another letter in May 2020.
Ms Pow told the court on Tuesday that she found his behaviour "terrifying".
Mr Kirk, who is representing himself at Exeter Crown Court, said he had been trying to contact Ms Pow's office for help in trying to sue South Wales Police.
He accused the force of framing him over a dispute about a fake machine gun that he had fitted to a vintage plane.
In May 2019, when the time the letter containing the white powder was sent, he was in prison for an unconnected offence of breaching a harassment order against a doctor.
Mr Kirk asked Judge Peter Johnson to allow him to consume the white substance which he sent to Ms Pow.
But he was told this was impossible because it had been treated with harmful chemicals during forensic examination.
"Will you allow me to suck it and see? Can I examine it?" he said.
"If you allow me, I will suck it and see so I can decide whether it is noxious, lethal or toothpaste. Even after all this time, it will still taste like prison toothpaste."
The court heard he had told officers that his arrest for harassing Ms Pow in May 2020 after his visit to her home was "utterly ridiculous" and that he found the allegation "insulting".
Mr Kirk, of Westgate Street, Taunton, is accused of one count of stalking that caused serious alarm or distress.
The trial continues.