One needs to remember that The Age during the 1990s always commented that many players would refuse to join Sydney if drafted. They indeed contemplated a court case overthrowing the draft entirely and creating a fully open player market.
Thus, the Swans cannot be deemed that easily to have done the wrong thing. It is a minor achievement that the draft has not been challenged (will an Abbott leadership produce judges more sympathetic to a challenge?) and that, despite the effect of Docklands in slowing the growth of the talent pool, there have not been notable appeals against a weak and poor club drafting a very promising player who does not want to play there. I have my suspicions that Melbourne, St. Kilda and perhaps the Bulldogs may have this problem in the near future however, and whether the legitimacy of the draft would be threatened is a good question. (It is easy to see how court judges could say the draft has propped up unviable clubs for a long period and that renders it illegitimate).
The collective bargaining agreement makes it almost impossible for a player who is a member of the AFLPA to challenge the draft. An 18 year old kid could but where is he going to find $2mil and 2 to 3 years to fight it.
In 1992 there was a CBA between the players and AFL but it was rather weak. See
http://en.wikipedia.org/wiki/AFL_Players_Association
The NSWRL lost their 1991 draft case in the full Federal Court on appeal by the players (who lost before a single judge) because the league and players didn't have a CBA and the players opposed a draft.
In the USA baseball has a legal exemption from anti trust laws but the Supreme Court saw this as an anomaly in the famous 1972 Flood v Kuhn case that baseball won 5-3, but lost in the court of public opinion and introduced free agency as a result. In the USA college players haven't challenged the draft but have said they wont accept being drafted by a particular team and go and do something else.
1979 #1 draftee Ohio State linebacker Tom Cousineau was taken as the top overall pick in 1979 by the Buffalo Bills, but he didn't want to play for the Bills and signed with the Canadian Football League's Montreal Alouettes.
1983 #1 draftee John Elway couldn't stand the thought of playing for Robert Irsay's Baltimore Colts and signed a contract with George Steinbrenner's Yankees. While Elway was patrolling the outfield for the New York-Penn League's Oneonta Yankees, the frustrated Colts dealt his rights to the Denver Broncos.
1986 #1 draftee Bo Jackson was pissed off that Tampa Bay Buccaneers' flew him on their private jet to check out their facilities and he asked if they cleared that it was all ok with the NCAA, they told him yes when they didn't check, but later the NCAA said this broke their rules and stopped him playing baseball in his final year at college, so he signed a contract with the Kansas City Royals and told them to get lost. Jackson did eventually play in the NFL for the Los Angeles Raiders.
Between 1983 and 1985 several players drafted by NFL teams didn't like who drafted them, so they went and played in the USAFL, in particular Jim Kelly who didn't want to go to Buffalo, but ended up there after the USAFL folded and became a legend.
And it isn't easy to win in court in the USA and it won't be in Oz but if an undrafted player challenges it, then only the 3 judges listening to the case will know whether it is possible or not. Remember that in 1991 the Full Federal court 3-0 overturned a single judge's decision to make illegal the forerunner to today's NRL - the NSW Rugby Leauge's draft.
I wrote a long post with references to US situation and court cases in the following post on the Port board.
http://www.bigfooty.com/forum/threads/what-to-do-with-the-port-magpies.1004084/page-4#post-28189474