The court's newest justice, Neil Gorsuch, will decide if unions have cause for worry.
Unions fearing a loss of mandatory fees will get access to recruit new workers.
Forecasters have little to go on since education wasn't a major theme in the presidential campaign.
The bill would mandate coaching for ineffective teachers and make it easier to fire them.
At stake is the ability of the CTA and public employee unions to charge mandatory fees.
Proposition 98 channels new revenue to schools to partially make up for past cuts.
Gov. Jerry Brown said last week he's open to changing tenure and other teacher employment laws at issue in the Vergara v. State of California lawsuit, and most teachers in a new survey say they want to change them, too.
