MLS
USA
| Referee | Games |  |  | Cards per game |
|---|
| Jasen Anno | 5 | 12 | 2 | 2.8 (2.4 / 0.4) | |
| Jozef Batko | 1 | 4 | 0 | 4.0 (4.0 / 0.0) | |
| Elias Bazakos | 6 | 17 | 2 | 3.1 (2.8 / 0.3) | |
| Fotis Bazakos | 6 | 11 | 0 | 1.8 (1.8 / 0.0) | |
| Andrew Chapin | 1 | 3 | 0 | 3.0 (3.0 / 0.0) | |
| Allen Chapman | 10 | 34 | 1 | 3.5 (3.4 / 0.1) | |
| Ismail Elfath | 8 | 21 | 4 | 3.1 (2.6 / 0.5) | |
| Drew Fischer | 6 | 15 | 0 | 2.5 (2.5 / 0.0) | |
| Matthew Foerster | 6 | 22 | 0 | 3.7 (3.7 / 0.0) | |
| Geoff Gamble | 11 | 33 | 0 | 3.0 (3.0 / 0.0) | |
| David Gantar | 7 | 14 | 4 | 2.6 (2.0 / 0.6) | |
| Mark Geiger | 16 | 56 | 10 | 4.1 (3.5 / 0.6) | |
| Jorge Gonzalez | 15 | 47 | 1 | 3.2 (3.1 / 0.1) | |
| Hilario Grajeda | 19 | 70 | 2 | 3.8 (3.7 / 0.1) | |
| Juan Guzman | 13 | 50 | 2 | 4.0 (3.8 / 0.2) | |
| Ramon Hernandez | 4 | 16 | 0 | 4.0 (4.0 / 0.0) | |
| Edin Jurisevic | 14 | 44 | 0 | 3.1 (3.1 / 0.0) | |
| Mark Kadlecik | 7 | 28 | 2 | 4.3 (4.0 / 0.3) | |
| Michael Kennedy | 6 | 22 | 1 | 3.9 (3.7 / 0.2) | |
| Jair Marrufo | 18 | 47 | 3 | 2.8 (2.6 / 0.2) | |
| Abbey Okulaja | 5 | 16 | 1 | 3.4 (3.2 / 0.2) | |
| Chris Penso | 20 | 44 | 2 | 2.3 (2.2 / 0.1) | |
| Silviu Petrescu | 19 | 60 | 1 | 3.3 (3.2 / 0.1) | |
| Yadar Reyes | 4 | 9 | 1 | 2.6 (2.3 / 0.3) | |
| Silvia Reyes | 1 | 3 | 0 | 3.0 (3.0 / 0.0) | |
| José Rivero | 8 | 32 | 4 | 4.5 (4.0 / 0.5) | |
| Ricardo Salazar | 4 | 16 | 2 | 4.5 (4.0 / 0.5) | |
| Ricardo Salazar | 13 | 37 | 2 | 3.0 (2.8 / 0.2) | |
| Sorin Stoica | 9 | 39 | 1 | 4.4 (4.3 / 0.1) | |
| Kevin Stott | 19 | 55 | 1 | 3.0 (2.9 / 0.1) | |
| Baldomero Toledo | 21 | 55 | 1 | 2.6 (2.6 / 0.0) | |
| Terry Vaughn | 3 | 13 | 0 | 4.3 (4.3 / 0.0) | |
| Armando Villareal | 8 | 21 | 5 | 3.2 (2.6 / 0.6) | |
| Paul Ward | 7 | 15 | 0 | 2.1 (2.1 / 0.0) | |
England