Pauline Broughton, 70, and 46-year-old Mel Broughton, the founder of activist group Speak, appeared before Oxford magistrates yesterday, the first day of an expected four-week trial.
They are charged in connection with a protest outside the Sheldonian Theatre during an Oxford University Encaenia ceremony on June 21 last year.
Prosecutor Gareth Branston said the protesters were spread across the junction of two busy main streets and used a megaphone to chant slogans voicing their protests against the laboratory.
Fearing the demonstrators were causing a serious disruption, police ordered the group to continue their demonstration at the Martyrs Memorial in nearby Magdalen Street.
But as the group began to walk away many protesters sat down and refused to move.
Mr Branston said: "One of the defendants, Mel Broughton, began to yell and gesture other protesters to hold their ground and protesters, as a result, sat down.
"Some linked arms and protesters, particularly the 16 defendants, made it clear to the police they would not comply with the conditions imposed."
After police arrested three protesters, the bulk of the remaining demonstrators began to disperse, Mr Branston told the court.
A further 13 were arrested after police reviewed camera footage of the demonstration. Mr Branston said officers used powers contained in the Public Order Act to force the protesters to move.
The protest, at a ceremony where academics receive honorary degrees, was held to campaign against the building of an animal testing laboratory for Oxford University in South Parks Road.
Pauline Broughton, of Welford Road, Northampton, is charged with breaching Sections 12 and 14 of the Public Order Act 1986, obstructing the highway and obstructing a police officer.
Mel Broughton, of Semilong Road, is charged with inciting others to breach Sections 12 and 14 of the Public Order Act 1986, breaching Sections 12 and 14 of the Public Order Act 1986, obstructing the highway and obstructing a police officer.
The trial continues.