Apple filed a motion late last week to vacate a court order obtained by FBI to create a special computer code to unlock the iPhone used by San Bernardino attacker Syed Rizwan Farook. One argument in Apple's motion is that code is a form of speech — and forced code from the government amounts to compelled speech and viewpoint discrimination in violation of the Constitution.

The issue is likely to come up Tuesday at a Capitol Hill hearing. In prepared testimony, Apple counsel Bruce Sewell said giving the government a tool to unlock iPhones would weaken the security of hundreds of millions of Apple devices.

While lower courts have ruled that computer coding is speech, Apple's argument enters thornier legal territory, experts said.