Ok, I have a friend at my old company that was on maternity leave for (I think) 3 months. When she called up to say she was returning, they laid her off. Is that legal?

company has about 40-50 employees, and has been downsizing in the field work force, she is office staff and there have been no lay offs in the office anytime recently.

That depends.

If she can show that she was selected for layoff BECAUSE she was out on maternity leave, that's illegal.

But if she would have been the one selected for layoff regardless of whether she went on maternity leave or not, that's legal.

That depends.

If she can show that she was selected for layoff BECAUSE she was out on maternity leave, that's illegal.

But if she would have been the one selected for layoff regardless of whether she went on maternity leave or not, that's legal.

Do you know who the burden of proof would be on?

Not quite. The presumption might just be against the employer. If no one else in her department was terminated but she was "singled" out and laid off, the rebuttable presumption would be that she was retaliated against and discriminated against for exercises her right under FEHA and PDLL to take pregnancy leave.

She likely has a legitimate claim that many employers would consider settling, especially if they make a prudent business decision.