The rally, which is being organized on Facebook, is in support of Mehserle, a former BART police officer, was convicted of involuntary manslaughter on July 8 for fatally shooting Oscar Grant III in the back on a platform at the Fruitvale BART station in Oakland on Jan. 1, 2009.
Mehserle's lawyer, Michael Rains, admitted that Mehserle shot and killed Grant, a 22-year-old Hayward resident, but said the shooting was accidental. He claimed that Mehserle had meant to use his Taser on Grant, but fired his service weapon by mistake.
A page about Monday's event on Facebook refers to it as the "In Support of Johannes Mehserle and L.E.O. (law enforcement officers) Rally," and says it will be held from 2 p.m. to 5 p.m. in the parking lot of the Walnut Creek courthouse at 640 Ygnacio Valley Road.
The description of the event on Facebook says the rally is meant "to show our support for Johannes, his family, and our law enforcement officers. This was a tragic mistake that occurred while on active duty."
Bryden said he doesn't know how many people are expected to attend the event. As of this afternoon, the Facebook page for the event listed 126 people planning to attend, but Bryden said that many people who support Grant also plan to gather there.
He said he did not know who was organizing the rally or why they chose Walnut Creek.
Walnut Creek police will be working with the Contra Costa County Sheriff's Office, which provides security for the courthouse, to monitor the rally.
Bryden said situations like this can be very emotional and potentially volatile, but "we are going to ensure that it's peaceful."
He said, "In cases like this we plan for the worst and hope for the best."
During protests in Oakland that followed the verdict, 78 people were arrested, many on allegations of unlawful assembly and failure to obey orders to disperse. Others, however, were arrested on suspicion of arson, causing property damage, and using an explosive device.
The Facebook page for Monday's rally says, "This rally is NOT about inciting violence, destruction, intolerance, hatred, racism, riots or to upset the Grant family...People who support law enforcement and Johannes have just as much right to rally together with other believers to have their voices heard and support one another."