The Supreme Court, by tradition, returns from its summer recess on the first Monday in October to begin a new term. Right off the bat, the justices will tackle several cases that raise important constitutional questions.

This will be the first full term with Justice Neil M. Gorsuch on the Court. President Trump nominated Gorsuch last January to fill the seat vacated by the death a year earlier of Justice Antonin Scalia; Gorsuch took his seat as one of the court’s nine justices in April (see graphic) after the Senate confirmed him.

Among the most anticipated cases on the Court’s docket are ones that deal with the constitutionality of President Trump’s temporary travel ban on people from six majority-Muslim countries; the right to privacy in the digital age; limits on the First Amendment guarantee of religious freedom; and the legitimacy of the political practice of gerrymandering.

Here’s what you need to know to understand those key cases.

The Supreme Court returns from its summer recess on the first Monday in October to begin a new term. It’s tradition. Right away, the justices will tackle several cases that raise important constitutional questions.

This will be the first full term with Justice Neil M. Gorsuch on the Court. President Trump nominated Gorsuch last January to fill the seat vacated by the death a year earlier of Justice Antonin Scalia. Gorsuch took his seat as one of the Court’s nine justices in April after the Senate confirmed him.

There are many anticipated cases on the Court’s docket this session. One major case deals with the constitutionality of President Trump’s temporary travel ban on people from six majority-Muslim countries. Others deal with the right to privacy in the digital age, limits on the First Amendment guarantee of religious freedom, and the legitimacy of the political practice of gerrymandering.

Is President Trump’s travel ban constitutional?

Trump v. International Refugee Assistance Project

This case pits two important constitutional concerns against each other. The Court will have to weigh the president’s power to safeguard America’s national security versus the First Amendment guarantee that people won’t face discrimination based on their religious beliefs.

“It’s one of the most important cases about religious liberty that the Supreme Court has ever heard,” says David Gans of the Constitutional Accountability Center, a legal think tank in Washington, D.C. “It poses the question: Can the president write religious discrimination into our immigration laws?”

The case stems from an executive order that President Trump issued with the intention of shutting down travel to the U.S. from six majority-Muslim countries—Iran, Libya, Somalia, Sudan, Syria, and Yemen—for 90 days. The order also temporarily blocked entry of refugees from any nation.

Trump said the order was necessary to give the Department of Homeland Security time to evaluate and address problems in the vetting process for visitors from countries it considers dangerous.

“We want to ensure that we are not admitting into our country the very threats our soldiers are fighting overseas,” Trump said.

The travel ban has its roots in a presidential campaign promise. In December 2015, then-candidate Trump called for a “total and complete shutdown” of Muslim immigration in response to the threat posed by terrorist groups such as ISIS (see “Are We Winning the War Against ISIS?”). Earlier that month, a Muslim-American gunman claiming to be acting on behalf of ISIS killed 14 people at an office party in San Bernardino, California. Trump’s proposal resonated with many Americans who were increasingly fearful about the threat of terrorist attacks on U.S. soil.

After human rights groups filed lawsuits to overturn the travel ban, federal appeals courts blocked two different versions of the ban, ruling that it discriminated based on religion, in violation of the First Amendment, and that it exceeded the authority given to the president by federal immigration laws. The Trump administration appealed the federal court rulings, and in June the Supreme Court agreed to hear the case. In the meantime, it allowed some parts of the travel ban to take effect.

Those who oppose the travel ban say the government has provided little evidence for how the ban would protect U.S. citizens. No one from the six targeted countries has killed an American on U.S. soil in a terrorist attack since at least 1975, according to a study by the Cato Institute.

But those who support the ban say the enormity of the potential security risks makes the restrictions reasonable.

“The vast majority of people coming from these countries don’t pose a threat, but it only takes a few people getting through the net to do an awful lot of damage,” says Ira Mehlman of the Federation for American Immigration Reform, a group that favors tighter restrictions on immigration.

Justices will hear oral arguments in the case October 10.

Does the government need a warrant to get cellphone location information?

Carpenter v. United States

How much access should the police have to cellphone data that could tell them where a person was at any given moment? The Supreme Court has ruled previously that police need to get a court-issued warrant before using GPS devices to track suspects’ movements or searching the contents of suspects’ cellphones.

The new case concerns historical data held by cellphone companies that shows users’ movements over time and could, for instance, place them at the scene of a crime. When you carry a phone, that device is constantly communicating with cellphone towers, which allows the phone company to have a pretty accurate picture of your location throughout the day. Currently, police aren’t required to obtain a warrant to get this location information from phone companies.

How much access should the police have to cellphone data that could tell them where a person was at any given moment? The Supreme Court has weighed in on a similar case before. They ruled that police need to get a court-issued warrant before using GPS devices to track suspects’ movements or searching the contents of suspects’ cellphones.

The new case concerns historical data held by cellphone companies. This data shows users’ movements over time and could, for instance, place them at the scene of a crime. When you carry a phone, that device is constantly communicating with cellphone towers. This allows the phone company to have a pretty accurate picture of your location throughout the day. Currently, police aren’t required to obtain a warrant to get this location information from phone companies.

This case is really about whether privacy survives in the digital age.

Police say tracing suspects’ movements can be critical to solving crimes. But privacy advocates argue that giving authorities automatic access to the information without a warrant is a violation of privacy rights under the Fourth Amendment.

“This case is really about whether privacy survives in the digital age,” says David Cole of the American Civil Liberties Union.

Police say tracing suspects’ movements can be critical to solving crimes. But privacy advocates argue that giving authorities automatic access to the information without a warrant is unlawful. It would violate Americans’ privacy rights under the Fourth Amendment, they say.

“This case is really about whether privacy survives in the digital age,” says David Cole of the American Civil Liberties Union.

Does a bakery have to provide services for a gay wedding?

Masterpiece Cakeshop v. Colorado Civil Rights Commission

In 2012, Masterpiece Cakeshop, a bakery in Lakewood, Colorado, refused to create a cake for the wedding reception of a gay couple, saying it was against the owners’ religious beliefs to support gay marriage.

The couple filed discrimination charges, arguing that they’re entitled to equal treatment from businesses that choose to serve the general public. A state civil rights commission and state courts ruled in their favor. The bakery owners appealed those rulings to the Supreme Court. They argue that the First Amendment guarantee of religious freedom means the government can’t force them to act against their faiths, even if it means turning away some customers.

The case could have major implications on the rights of business owners to discriminate based on their religious beliefs. It comes two years after the Supreme Court legalized same-sex marriage nationwide.

In 2012, Masterpiece Cakeshop, a bakery in Lakewood, Colorado, refused to create a cake for the wedding reception of a gay couple. The bakery’s owner said it was against his religious beliefs to support gay marriage.

The couple filed discrimination charges. They argued that they’re entitled to equal treatment from businesses that choose to serve the general public. A state civil rights commission and state courts ruled in their favor. The bakery appealed those rulings to the Supreme Court. The owner argues that the First Amendment guarantee of religious freedom means the government can’t force him to act against his faith, even if it means turning away some customers.

The case could have major implications on the rights of business owners to discriminate based on their religious beliefs. It comes two years after the Supreme Court legalized same-sex marriage nationwide.

Is partisan gerrymandering constitutional?

Gill v. Whitford

Gerrymandering, the process of drawing oddly shaped legislative districts for political advantage, is a centuries-old practice.

The Supreme Court has declared the practice unconstitutional when done for racial reasons—to try to dilute the voting power of a racial group.

In this case, which concerns legislative districts drawn by the Wisconsin State Assembly after the 2010 census, the question is whether it’s OK to rejigger district boundaries to give one political party a clear advantage.

Critics of gerrymandering say that technology now allows lawmakers to draw district maps that ensure victory for their party—denying supporters of another party the right to fair representation. A ruling that limits partisan gerrymandering could have enormous implications for American politics.

Upfront will be taking an in-depth look at gerrymandering and this case in an upcoming issue.

Gerrymandering is the process of drawing oddly shaped legislative districts for political advantage. It’s a centuries-old practice.

The Supreme Court has declared the practice unconstitutional when done for racial reasons. This includes using the method to try to reduce the voting power of a racial group.

This case concerns legislative districts drawn by the Wisconsin State Assembly after the 2010 census. It raises the question of whether it’s OK to rejigger district boundaries to give one political party a clear advantage.

Critics of gerrymandering say that technology now allows lawmakers to draw district maps that ensure victory for their party. That denies supporters of another party the right to fair representation, they say. A ruling that limits partisan gerrymandering could have enormous implications for American politics.

Upfront will be taking an in-depth look at gerrymandering and this case in an upcoming issue.