The Florida Legislature in 1996 erroneously passed the law as a general act covering the entire state, the justices said in a unanimous opinion. They found it should have been a local bill because it affects only three South Florida tracks.
As a result, lawmakers failed to hold a public hearing or give notice in the affected area as the Florida Constitution requires for local bills.
The high court upheld two lower court decisions that also found the law unconstitutionally restricted three South Florida tracks.
"It's going to help expand the industry," said Bruce David Green, a lawyer for the Florida Horseman's Benevolent and Protective Association. "It opens the area for competition and that's not a bad thing."
The association of horse owners and trainers participated in the case as a friend of the court. They will benefit from higher pursues expected from the increased simulcast wagering, Green said.
The law prohibited Gulfstream Park, which challenged the statute, and other horse tracks from simulcasting from other venues except when holding their own live races. It also prohibited them from showing harness and dog racing or jai alai at any time.
The limits applied only to areas where three Thoroughbred or harness tracks are within 25 miles of each other. The only place that fits that description is the border area of Miami-Dade and Broward counties that includes Gulfstream in Hallandale and Calder Race Course in Miami, both Thoroughbred tracks, and Pompano Park, a harness track, in Pompano Beach.
The law aided South Florida greyhound and jai alai frontons by limiting competition from the horse tracks.
Lawyers representing those interests, which joined the state in defending the law, did not immediately return a phone message seeking comment.
Circuit Judge Jonathan Sjostrom initially ruled the law unconstitutional. He said it appeared the simulcasting limits had been placed on Gulfstream in exchange for other benefits the track received from the state.
"This sort of local interest horsetrading is specifically prohibited" by the Florida Constitution, Sjostrom said.
The 1st District Court of Appeal sustained his ruling. The law's supporters argued in their Supreme Court appeal that it should be considered a statewide statute because the Tampa area in the future also might meet its criteria.
That could happen only if two quarter horse tracks are built within 25 miles of Tampa Bay Downs, the only other Thoroughbred track in the state.
The South Florida tracks opened before the state limited the placement new horse and dog tracks or frontons within 100 miles of an existing pari-mutuel facility. Quarter horse tracks are exempt from that restriction but that type of racing no longer exists in Florida because it proved to be unprofitable.