The Supreme Court has three blockbuster cases on the docket this week.

The big picture: One has the potential to deal a crippling blow to public-sector unions; another dives into email privacy vs. law enforcement; and the third centers on free speech at the polls.

1. Janus v. AFSCME: For years, the court has been inching closer and closer to ruling that public-sector unions can't collect fees from non-members.

• It’s widely expected to finish the job in this case. Oral arguments are Monday.
• The court will likely roll back one of the few remaining strongholds of union power — and with it, the political clout of an important part of the Democratic base.

2. US v. Microsoft: If an American email provider stores your emails on a server that's located in another country, does it have to hand those emails over in response to a warrant from U.S. law enforcement? That’s the question in US v. Microsoft, which the court will hear Tuesday.

• The Justice Department argues that if these warrants don’t cover overseas servers, the court will be carving out an awfully easy route to get away with crimes like drug trafficking and child pornography.
• Microsoft, on the other hand, says allowing those warrants would open the door for foreign governments to unilaterally access data stored in the U.S.

3. Minnesota Voters Alliance v. Mansky: A Tea Party voter wore a Tea Party t-shirt to his polling place on Election Day. But Minnesota, where he lives, bans political apparel at polling places, so he was asked to cover up the Tea Party messages while voting. Is that a violation of his right to free speech, or a permissible restriction on electioneering?

• Under Chief Justice John Roberts, people who allege an infringement of their First Amendment rights usually win.

Bottom line: The court also has cases on the docket this term about gerrymandering, the privacy of cell-phone location data, whether a Christian baker can refuse to serve a same-sex couple, and President Trump’s travel ban. And then there’s the consistent speculation about whether Justice Anthony Kennedy will retire.