The NFL and the NFL Players Association are reviewing concussion protocol procedures after New York Giants receiver Sterling Shepard suffered a concussion against the Dallas Cowboys in Week 1 but was permitted to finish the game, according to Adam Schefter of ESPN.

Shepard has been ruled out of Sunday's game against the Buffalo Bills.

During the third quarter of Sunday's season opener, Shepard collided with Cowboys cornerback Anthony Brown and fell to the ground. Though the 26-year-old wideout appeared to be shaken up, he was not removed from the game.

Schefter noted just three out of 1,200 concussion evaluations over the past two seasons have been reviewed. All three, which involved Seattle Seahawks quarterback Russell Wilson, then-Houston Texans quarterback Tom Savage and Carolina Panthers quarterback Cam Newton, occurred during the 2017 season.

Back in 2013, the NFL began employing independent concussion specialists to work down on the sidelines for every game. Those experts have been asked to attempt to identify players who may be experiencing concussion symptoms and remove them from the game for further testing.

The specialists reserve the right to hold players out of action regardless of what team physicians may decide.

Ken Belson of the New York Times reported in July 2016 that teams that violate protocol will be subject to "hundreds of thousands of dollars" in fines and the loss of draft picks.

The NFL has faced a number of lawsuits relating to concussions in recent years. The league reached a $765 million settlement back in August 2013, which was used to compensate victims, pay for medical exams and underwrite research.

In April 2015, Senior U.S. District Judge Anita Brody approved a plan for the NFL to resolve lawsuits by paying out approximately $1 billion—split between more than 20,000 retired players—over 65 years.