On three occasions since May, tempered glass panels at the downtown San Diego state courthouse have shattered, forcing court officials to construct a canopy around the high-rise building to protect people on the sidewalks below.

In an email sent Monday to judges and court staff, San Diego Superior Court Presiding Judge Michael T. Smyth and court Executive Officer Michael Roddy said the $555-million building had “experienced three recent incidents of spontaneous breakage of tempered glass panels.”

The unexplained breaks occurred both on the interior and exterior of the 22-story San Diego Central Courthouse.

The state Judicial Council, the policymaking arm of the judicial branch that constructed and owns the building, is investigating what caused the breaks. In the email, Smyth and Roddy wrote there could be several possible reasons such as “impacts, impurities in the glass, high temperatures or other causes.”

The breaks have occurred on different sides and floors of the building. Windows on the 10th, 12th and 14th floors have shattered or broken since May, according to court spokesperson Emily Cox. No one has been injured.

Ethics officials said former City Councilman Mitchell Englander violated various gift laws when he accepted cash and other perks from two businessmen.

Blaine Corren, a spokesman for the Judicial Council, said the first incident occurred on May 16 when an exterior glass pane shattered in place — meaning it was not dislodged — on the 14th floor of the north side of the structure.

On July 5 an interior pane on the 10th floor shattered, also in place, on the west side.

The most recent shattering incident occurred on Aug. 4 on the opposite side of the building when an exterior pane on the 12th floor facing east broke, Corren said.

The window fell out sometime before Aug. 8, with the glass tumbling eight floors to what he described as an interior rooftop service-area courtyard on the fourth floor. No glass landed on the street or sidewalk in any of the incidents.

Nonetheless, the state has decided to construct an 8-foot-high sidewalk canopy around the perimeter of the building until it can determine what is causing the problem. Construction was intended to begin Tuesday, but the state has not yet hired a contractor to do the work, Corren said.

Meanwhile, the state will try to figure out what’s causing the breaks. “The council is in the process of retaining experts to evaluate the window conditions,” Corren wrote in an email. “We do not know how long the investigation will take at this point but expect to have additional information soon.”

This is not the first problem with the windows at the building, which opened to the public in December 2017. A broken window on an upper floor along the north side of the building shut down the sidewalk for weeks in early 2018 while awaiting repair.

About nine months after the opening, in September 2018, the court had to replace windows in 22 judges’ chambers because of a “crazing,” or extensive cracking, defect. The repair costs were covered by the construction warranty of the contractor, Rudolph & Sletten.

Corren said there is no cost estimate yet for the window repair and canopy work but said the state will work to recover the repair and other related expenses from the contractor.

It is not known how long the canopies will have to remain in place. The two court executives said in the email that global supply-chain problems have delayed delivery of the replacement glass.

When the courthouse opened in 2017, it was a year later than court officials had wanted due to a balky smoke control system that delayed approval by the state fire marshal. At the time it was the largest and most expensive courthouse built by the state.

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Greg Moran is a reporter covering criminal justice and legal affairs issues on the Public Safety team. He has worked for the Union-Tribune since 1991. He covered state, federal and appellate courts for 17 years. He has also been an investigative reporter on The Watchdog team and a reporter on the enterprise reporting team. He is a graduate of Carleton College and previously worked at newspapers in Minnesota and New York.