Only three NBA players have actual no-trade clauses built into their contracts:  Kobe Bryant, Dirk Nowitzki and Tim Duncan.

While technically they can be traded, it’s up to those individual players to allow any transaction.

For the coming season, the list of players with the power to block trades is a lot longer than the aforementioned three.  A variety of circumstances can create an implicit no-trade clause.

Matched Offer Sheets

When a restricted free agent signs an offer sheet that is matched by their original team, they have the ability to veto any trade for a full year.

Nicolas Batum of the Portland Trail Blazers signed an offer sheet on July 15th with the Minnesota Timberwolves.  Since the Blazers matched, Batum can block a trade through July 14th of 2013.

This also applies to Eric Gordon of the New Orleans Hornets.

Since most players ink during the summer, it rarely impacts the next season but with the lockout, a few stragglers remain.  DeAndre Jordan of the Los Angeles Clippers signed his offer from the Golden State Warriors on December 11th.  He can’t be dealt until mid-December without his consent.

The same can be said of Marc Gasol and Luc Richard Mbah a Moute

One-Year Bird

Another path to trade veto power involves a team re-signing a player, who would have either Bird or Early Bird Rights, to a one-year contract.  Even if a player signs for two years with the second a player or team option, that still falls in line with the trade restriction.

For example, the Blazers re-signed J.J. Hickson for one season at $4 million and since they have his Bird Rights, Hickson can block any trade.

Brandon Rush is back with the Golden State Warriors on a two-year deal with a player option on the second year.  He too has trade veto power.

A long list of players have the same authority including: Chauncey Billups, J.R. Smith, Keyon Dooling, Delonte West, Darius Morris, Marreese Speights, Patty Mills, Boris Diaw, Aaron Gray, Luke Harangody and Cartier Martin.

Of course if the team has the option, that franchise can simply lock in the second year and then execute a trade – although that’s not the case for any of the players mentioned.

Also Hamed Haddadi, who signed a two-year deal with the Memphis Grizzlies but the second year is partial/non-guaranteed (different than a team option), doesn’t gain the one-year Bird trade veto.

Alan Anderson’s rights were waived by the Toronto Raptors before the team re-signed him for a year, so he too doesn’t gain any veto power.

Amnesty Claim

In the case of players claimed off of amnesty waivers, they cannot be traded for the entire season (until the following July).  It’s not a matter of the player waiving their rights . . . it’s just illegal.

The following players were claimed this summer:  Elton Brand, Luis Scola and Brendan Haywood.  Since Brand is on a one-year deal, he will finish his contract with the Mavericks unless waived.

Other Restrictions

The Collective Bargaining Agreement has a laundry list of rules limiting player availability in trade.

Teams need to wait 30 days to trade a signed first-round draft pick.  For instance if the Cleveland Cavaliers wanted to send Tyler Zeller and/or Dion Waiters to the Orlando Magic in a three-way trade with the Los Angeles Lakers, they’ll have to wait until at least August 4th.  The 30-day clock is almost over for Houston Rockets’ rookie Donatas Motiejunas but there are still some weeks left to wait on the contracts of Terrence Jones, Royce White and Jeremy Lamb.

It’s unclear if any would specifically be offered up in the Dwight Howard chase but if any are key, potential components, that might be the reason for delay.

Regular free-agent signings over the summer prevent a player from being dealt until December 15th (or three months after the contract is signed, whichever is later).  To pick a random example, Carl Landry of the Golden State Warriors can’t be moved until mid-December.

Also, the list of players who signed offer sheets (whether matched or not) can’t be dealt until December 15th.

Anyone claimed off waivers during the offseason can’t be traded until 30 days into the season, which applies to Jon Leuer of the Cleveland Cavaliers.

Because Brook Lopez, of the Brooklyn Nets, got a raise greater than 20%, he can’t be traded until January 15th.  This applies only to players re-signed by their existing team (who happens to be over the cap) via Bird (or Early Bird) rights who made more than the minimum last season (which includes Ersan Ilyasova).

With their respective teams over the cap, it doesn’t apply to Eric Gordon, Nicolas Batum or Roy Hibbert who can be dealt once December 15th hits.  Of the three, only Hibbert lacks the implicit no-trade clause.

If a team is over the cap, they can’t package a recently acquired player in trade with another for two full months.  For example, the Atlanta Hawks wouldn’t be able to bring in a player making $9 million by combining the salaries of Anthony Morrow and Johan Petro – at least until September.

Conversely, the Rockets are under the cap so they can deal Shaun Livingston packaged with Toney Douglas, despite both recently coming to Houston via trade.

While there are other rules that come into play during the season, including the obvious – a player can’t be traded after the trade deadline – another pertinent restriction is the year-round is a ban on teams re-acquiring a player they recently traded away.

Rumors had Brad Miller going back to the Minnesota Timberwolves, which would have been simply illegal.  Instead he was dealt to the Phoenix Suns.  Technically a player can be traded near the draft in June and then reacquired in July.  The restriction runs NBA calendar year from July 1st to June 30th.

An important in-season rule to note is the 15-man roster limit.  During the offseason, there is a soft limit on 20-players (which at times has been exceeded by the Rockets this summer).

Teams cannot make trades during the season that pushes the roster count to over 15.  Incoming players cannot be waived to make room, only existing ones.

For example, if a team has 14 players and wants to send out three to bring in five, that would be illegal with a total-roster count of 16.  To execute such a deal, the team would have to first waive an additional player to open up a roster spot.

A potential Howard trade might be easier to execute over the summer given a high roster count is allowed, especially if the Rockets are involved with their army of cheap, non or partial-guaranteed contracts.

Finally, the Clippers cannot trade Blake Griffin until approximately January 11th since he signed a contract extension larger than what he could have gotten via extend-and trade.  Naturally, these are the rules . . . they don’t reflect what a team might actually want to do.  It’s safe to say the Clippers have no intention of dealing Griffin once his restriction is lifted.

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