LONDON -- English referees chief Mike Riley has called for on-field officials to have access to video assistant referee (VAR) monitors at pitch level in order to make "subjective decisions" as the new technology is integrated into the game.
VAR was used twice in a friendly between France and Spain on Tuesday, once to rule out a goal from Antoine Griezmann and once to confirm a goal for Spain's Gerard Deulofeu.
Griezmann had headed the ball into the net and was in full celebration mode with his France teammates when referee Felix Zwayer pinned a finger into his left ear to block out the stadium noise.
An assistant in front of a bank of monitors was assessing replays and informed Zwayer through his earpiece that a player was offside in the buildup.
The goal was then ruled out, without Zwayer seeing a replay. But that won't necessarily be the case by the time video replays are fully approved to be rolled out across football, if Riley, manager of the Professional Game Match Officials Board (PGMOB), has his way.
For now, the experimental phase is still in full flow, but refereeing leaders believe officials should always have access to the footage themselves around the field.
"The subjective decisions should be made by the on-field referee because they have got the feel for the game," Riley said. "They can put it in the context of everything else. So as part of the process we have got to work out how we can do that as effectively as possible ... without interrupting the flow of the game."
The International Football Association Board, the game's lawmaking body, is in its second year of trials with various versions of VAR. Some games, like the France-Spain friendly, do not allow the referee to evaluate incidents and instead rely on the VAR.
But VAR could end up only ruling on what Riley describes as "decisions of fact," such as whether a ball was inside or outside the penalty area.
Ultimately, if you are appointing one of the top referees to preside over a major game, that person is seen as ideal for making the big calls, according to IFAB.
"Fundamentally we are told very much by players and coaches they want the referee to be making the most important decisions," IFAB technical director David Elleray said, referencing England's top referees. "They don't know who is in a van out in the car park or 300 miles away in a match centre."
Soccer's lawmakers only envisage video replays being used to correct game-changing decisions involving four situations: penalties awarded, red cards, cases of mistaken identity and goals scored.
"Nicola Rizzoli was appointed to referee the last World Cup final because he is the best referee," Elleray said. "But if actually the two most important decisions in the match are made by somebody watching a TV screen ... the most important person is the man you put behind the TV screen, not the man on the field."
The challenges come down to how on-field referees would be able to view replays without lengthening the delay, something Griezmann and France teammate Hugo Lloris complained about after the match.
For now the technology isn't satisfactory for officials to use wearable devices and receive footage in real time, according to Riley. That means going to the side of the field to watch incidents with the eyes of thousands of fans in the stands on them. The screens are likely to be on the opposite side to the technical area to avoid coaches being able to surround and harangue the referee.
"Some of our stadiums don't lend themselves to monitors by the side of the pitch because they are really tight," said Riley, a former Premier League referee who is now in charge of appointments for games in the world's richest football competition. "Is it right for referees to have to run 30 yards to go and look? Can you get the footage to the referee on the field somehow?
"All these things have to be explored through the experiment and come out with a solution that works for football."
Live experiments are taking place in about 20 competitions this year, including the Confederations Cup in Russia in June and July that will serves as a World Cup test event.
Once IFAB adds video replays to the laws of the game, any competition meeting the requirements will be able to use them.
For Riley, permitting replays is "the most significant change in refereeing in the game for generations," far more significant than the 2012 decision to allow technology that simply determines whether the ball crossed the goal line.
Riley said: "If you are making such a significant change, you need to really explore and understand all the potential implications."