Facebook has put itself at the forefront of efforts to recruit a more diverse workforce, including a targeted internal recruiting strategy in 2015 designed to bring in female, black and Latino software engineers.

Yet within Facebook's engineering department, the push has been hampered by a multilayered hiring process that gives a small committee of high-ranking engineers veto power over promising candidates, frustrating recruiters and hindering progress on diversity goals.

Facebook started incentivizing recruiters in 2015 to find engineering candidates who weren't already well represented at the company — women, black and Latino workers. But during the final stage for engineering hires, the decisionmakers were risk-averse, often declining the minority candidates.

The engineering leaders making the ultimate choices, almost all white or Asian men, often assessed candidates on traditional metrics such as where they attended college, whether they had worked at a top tech firm, or whether current Facebook employees could vouch for them, said former recruiters, who asked not to be identified.

Focusing on where someone went to school or whom they know in the company can often exclude candidates from underrepresented backgrounds, said Joelle Emerson, a diversity consultant who helps tech companies make their hiring more inclusive. "The fact that people are doing hours of interviews and then getting into a room and then talking about where people went to school seems like the most baffling waste of time."

The final step should focus on how candidates performed during the interview process, she said.

"Facebook recruits from hundreds of schools and employers from all over the world, and most people hired at Facebook do not come through referrals from anyone at the company," a company spokeswoman wrote in a statement. "Once people begin interviewing at Facebook, we seek to ensure that our hiring teams are diverse. Our interviewers and those making hiring decisions go through our managing bias course and we remain acutely focused on improving our ability to hire people with different backgrounds and perspectives."

Despite efforts by recruiters, Facebook's demographics in technology roles — which includes engineers and some other job categories — have barely changed, according to its yearly diversity reports. From 2015 to 2016, Facebook's proportion of women in tech grew from 16 to 17 percent, and its proportion of black and Latino U.S. tech workers stayed flat at 1 and 3 percent.

At most Silicon Valley companies, women, Latino and black employees are a small percentage of the workforce. Facebook has portrayed itself as a leader in the effort to change that, with executives giving public speeches on benefits and best practices.

Chief Operating Officer Sheryl Sandberg has been a strong advocate of promoting and encouraging women in the workplace.