COLLEGE STATION, Texas -- We've seen a lot of posts on social media, saying that those who choose not to stand during the national anthem are breaking the law.

That is false.

There are parts of US law that say civilians, those in uniform (like police), and active military or veterans "should" stand during the anthem.

But according to legal expert and professor at Cornell University and Elmira College, Jim Johnson, laws that say "should" instead of "shall" or "must" are optional.

"There's nothing compulsory in here," says Johnson. "If they wanted it to be compulsory, they would have said 'shall' or 'must.'"

Many facebook and twitter posts call out NFL players and owners, arguing those that kneel during the anthem are breaking Title 36, Section 301 of the US Code.

That law is real, it was signed by President George W. Bush in 2008. But, it's being misinterpreted.

The law provides guidelines for how different groups should act during the anthem. For civilians, it says they "should face the flag and stand at attention with their right hand over the heart."

But, because that law uses the word "should" instead of "shall," Johnson says its more of a guideline than mandatory.

According to Johnson, using "should" was a conscious choice by the group that wrote the law, part of a process called legislative drafting. So, it was never anyone's intention to make standing for the anthem mandatory for all US citizens.