Protesters opposed to President Obama's address to the graduating class of Notre Dame were arrested Friday after they disobeyed rules about staging their demonstration and walked onto the university campus.
Obama is also receiving an honorary law degree on Sunday, a decision that has upset abortion opponents who say the Catholic university is violating its own beliefs by honoring the president.
Protesters were told they could protest all they want in the town of South Bend, Ind., but once they stepped onto Notre Dame property, they would be arrested.
Former Republican presidential candidate Alan Keyes, and a Roman Catholic priest were among the 21 arrested.
"Notre Dame is arresting a priest," the Rev. Norman Weslin, founder of the Lambs of Christ abortion protest group, said as Notre Dame security personnel put plastic restraints on his wrists. "Why are you arresting a priest for trying to stop the killing of a baby? You've got it all backward."
Weslin, 78, who has been arrested dozens of times at abortion clinic blockades, was carried off on a stretcher. He and two others were charged with resisting law enforcement.
All 21 arrested were charged with trespassing. Keyes and five others were ordered held in the St. Joseph County Jail until Monday because it was their second time being arrested on a charge of trespassing at Notre Dame, said Sgt. Bill Redman, St. Joseph County Police Department spokesman. Bond was set at $250 for the others.
None of those arrested were students.
The arrests marked the third straight Friday people were arrested as they protested the school's decision to give Obama, who supports abortion rights and embryonic stem-cell research, an honorary degree and have him speak at commencement.
On May 1, anti-abortion activist Randall Terry and another man were arrested on campus while pushing strollers containing dolls covered in fake blood. On May 8, Keyes and 21 others, many of them pushing strollers containing dolls covered in fake blood, were arrested.
On Friday, there were no strollers or bloody dolls, but some of the protesters carried signs that read: "Defend her honor, rise and strike for the unborn."
About 35 people, many of them carrying anti-abortion signs, were standing on the four corners outside the school's front gate shortly before noon when a group of about 40 people led by Keyes and Terry marched up. They stopped briefly to say some prayers and to listen to Keyes, who lost to Obama in the Illinois Senate election in 2004.
"It is not consistent with God's love to honor those who have rejected that great gift of love in principle," Keyes said.
After speaking, Keyes then led a smaller group onto campus. They made it about 100 yards on campus before they were stopped by campus security. Keyes was taken into custody immediately, and the others were told to leave or they would be arrested.
Terry did not go onto campus, saying did not want to get arrested because he needs to remain free to lead more protests Saturday and Sunday.
"The reality is that if I get hung up in jail, I'm the only guy on the outside who knows how to keep this thing moving. It's strictly a leadership issue," he said.
St. Joseph Superior Court Judge Michael Scopelitis issued an order Thursday changing how bond is set for a person charged with a crime while already out on bond on a pending charge. Previously, such a person could have been released under a presumptive bond schedule. Now they must await a probable cause hearing, Scopelitis said.
The judge said county judges already were considering the change because of people being arrested multiple times and being released without appearing before a judge. He said the fact there could be numerous arrests this weekend surrounding Notre Dame's commencement brought the issue "into focus."
The Associated Press contributed to this report.