You have 3 wishes...

Okay, the last time the players got ahold of 3 wishes, they warped my campaign!

So I want to be prepared this time around.

What rules do you use for adjudicating wishes?

transcendation

If the wishes warped your game, then it sounds like those wishes should have warped the wishers. It might sound heavy handed or churlish, but if one gets greedy with a wish, the wisher may wind up needing to use more wishes to undo the grief. A PC can easily avoid getting screwed over by choosing the selected options wish gives.

Even wish, however, has its limits.

A wish can produce any one of the following effects.

Duplicate any wizard or sorcerer spell of 8th level or lower, provided the spell is not of a school prohibited to you.
Duplicate any other spell of 6th level or lower, provided the spell is not of a school prohibited to you.
Duplicate any wizard or sorcerer spell of 7th level or lower even if it’s of a prohibited school.
Duplicate any other spell of 5th level or lower even if it’s of a prohibited school.
Undo the harmful effects of many other spells, such as geas/quest or insanity.
Create a nonmagical item of up to 25,000 gp in value.
Create a magic item, or add to the powers of an existing magic item.
Grant a creature a +1 inherent bonus to an ability score. Two to five wish spells cast in immediate succession can grant a creature a +2 to +5 inherent bonus to an ability score (two wishes for a +2 inherent bonus, three for a +3 inherent bonus, and so on). Inherent bonuses are instantaneous, so they cannot be dispelled. Note: An inherent bonus may not exceed +5 for a single ability score, and inherent bonuses to a particular ability score do not stack, so only the best one applies.
Remove injuries and afflictions. A single wish can aid one creature per caster level, and all subjects are cured of the same kind of affliction. For example, you could heal all the damage you and your companions have taken, or remove all poison effects from everyone in the party, but not do both with the same wish. A wish can never restore the experience point loss from casting a spell or the level or Constitution loss from being raised from the dead.
Revive the dead. A wish can bring a dead creature back to life by duplicating a resurrection spell. A wish can revive a dead creature whose body has been destroyed, but the task takes two wishes, one to recreate the body and another to infuse the body with life again. A wish cannot prevent a character who was brought back to life from losing an experience level.
Transport travelers. A wish can lift one creature per caster level from anywhere on any plane and place those creatures anywhere else on any plane regardless of local conditions. An unwilling target gets a Will save to negate the effect, and spell resistance (if any) applies.
Undo misfortune. A wish can undo a single recent event. The wish forces a reroll of any roll made within the last round (including your last turn). Reality reshapes itself to accommodate the new result. For example, a wish could undo an opponent’s successful save, a foe’s successful critical hit (either the attack roll or the critical roll), a friend’s failed save, and so on. The reroll, however, may be as bad as or worse than the original roll. An unwilling target gets a Will save to negate the effect, and spell resistance (if any) applies.

You may try to use a wish to produce greater effects than these, but doing so is dangerous. (The wish may pervert your intent into a literal but undesirable fulfillment or only a partial fulfillment.)

What is the source of the wishes? A ring?

A benevolent source (e.g. a god for whom you've done a favor) will grant you what you want even if you word your request poorly, within the limits of the spell's power.
A neutral source (e.g. a ring) will be relatively literal but not abusively so. Usually only a problem if you say something *truly* stupid like King Midas.
An evil source (e.g. an efreet) will twist wishes as much as possible. If you out-lawyer them so the wishes can't possibly harm you, they'll likely harbor resentment and try to kill you later. You're better off not even trying to play their game.

My own guidelines are intended to PREVENT the game from becoming "Warriors & Lawyers." Vast tolerance of simply-phrased wishes. Complete intolerance for legalistic wishes. I know we're getting into House Rules here.

1) No matter the source of the Wish, the one making the wish pays any cost beyond the first 5,000 XP. Particularly important when wishing for magic items.
2) For the neutral source, do NOT abuse interpretation in a way that a non-gamer would consider ludicrous. If somebody says "I wish for a Holy Avenger sword," don't have it appear sticking through their chest and don't make it Colossal. They get a Holy Avenger sword sized for them and it costs a 9,600 XP (double the crafting XP cost). If somebody says "I wish to be stronger," that's a +1 inherent bonus to strength, not a polymorph into a Elder Black Pudding. This encourages straightforward Wishes.
3) Balancing this relative tolerance on wording should be a house rule on word limits. Perhaps no more than 1 word per caster level. Perhaps no subordinate clauses. Perhaps all Wishes are ultimately granted by gods who can choose to simply refuse any lawyered wishes (and the Wish is then wasted).
4) Some things are beyond the power of a Wish. It's a 9th-level spell, not an Epic spell or a divine ability. If a PC wishes for something beyond the power of a Wish, it just fails. Wishing for the death of a given NPC who is miles away is basically an unlimited-range Finger of Death; that's beyond a 9th-level spell. Wishing for the death of one nearby would still allow a saving throw and SR and be blocked by Death Ward. Time travel is not possible, nor raising multiple slain allies, nor a True Resurrection, nor a true prediction of the future (since PC actions can change the future, after all, not even gods know how the dice will fall).
5) If you wish, a principle of an economy of power in some cases. I wouldn't use this myself but it's an idea I've seen around. If a character says "I wish for a flaming magical longsword," one can be transported instead of created. This would not require an XP cost, since the Wish is not creating the item. A sword being taken from an NPC and transported to the PC in response to a wish is a) not so lawyerly as to be antithetical to legends/myths/etc. (Helen of Troy springs to mind); and b) good for plot hooks.

I agree with Brother MacLaren regarding how different sources may interpret wishes..

My HR regarding the verbage is simple:

Your wish must be stated verbally as one sentence that does not contain conjunctions, such as 'and'. It must be spoken in character, no game mechanic language is allowed.

I really like that WOTC put explicit capabilities on the spell, but have always gone the route of least expenditure of power, teleporting objects instead of creating them.
This has the advantage of the previous owner casting divinations to track them down

In some 2e games I did earn a reputation for some pretty nasty twistings of Wishes... to the point where a player demanded the destruction of a Sword of Wishes that was found... but most of the time it was simply wording that could be easily taken wrong literally.

Key point: If you want the power of the Wish in the players hands.. don't let the item exist in your game. If its in your game... go with the limits in the PHB and let the players have fun.

Can't see Wishes in 3.5 warping a game overly.

Things to consider:

1. Who is granting the wish?
They may have an agenda of their own and, as long as the wish is granted to the WORDS, the INTENTION may be twisted.

2. How did the player word the Wish?
Make sure the player says the Wish out loud and note it down word for word. Don't give them a do-over. Something as powerful as a Wish demands respect - if they don't respect the power they don't get exactly what they want.
Poorly thought out and/or phrased Wishes are a godsend to DMs. See 1 above.

if they make a wish that is to powerful it fizzels but the caster should know how powerful his spell is and might tell a wisher that what they ask is outside its power

i don't advise warping wish in less they are for a evil source after all it is most likely they are getting hold of these wishs as a reward not a punishment

P.s. if you character is really smart say 16 or better then out of game tell the DM what you want done and let him word it so it happens correctly. DM's i sugest in this case just say they said it correctly to get desired results to save time and headach.

The key restricting phrase ois this:

You may try to use a wish to produce greater effects than these, but doing so is dangerous. (The wish may pervert your intent into a literal but undesirable fulfillment or only a partial fulfillment.)

You don't need to pervert the wish, you can always just do partial fulfiillment. Look at what 8th level spells can do and use that as the limit.

Tell the players that they shoujld read the wish spell, and if they ask for anything that is too powerful you will just partly fulfil it or distort it. Tell the players that they will not break your campaign with a wish.

If they wish for a +5 sword, partly fulfill it. give them a +1 sword. Or give them a +5 sword, but take away XP and treasure from the person who made the wish to pay for the sword (perhaps less the 5000xp of the wish)

If they wish for a +1 stat then give them that.

Don't bother perverting the wish

Ditto what Veril said. Really, the wish rules are pretty functional. You can get a small treasure (25,000gp), boost your stats, raise people from the dead, etc.

Consider having your party mage/cleric make a spellcraft check (DC:15 or 20) that know that making a specific wish is more dangerous than simply making your general desire known. Asking for "a big pile of money" is safer than "1,000,000 gold pieces." Wishing for "a useful, enchanted blade" is better than "a vorpal blade."

The most important thing is to not screw people who use the wish in the bounds of the rules. No word games, no semantics. Wishes are reality-bending magic, they should be able to comprehend the intent.

That way when someone gets greedy and crosses the line they get no sympathy.

I've never actually cast a Wish in play. I've had characters who had access to them (three times), but never used it. In two cases it was an item, and I vastly prefer to keep such items for an emergency (see the "undo misfortune" bullet). In the third case, my wizard just never got a good opportunity to dump 5k xp.

That said, if I ever did try to use them and got hosed for no good reason, I'd be looking for a new DM. If your players are asking for something reasonable (especially anything on the bulleted list), give it to them. Don't make it into an adverserial thing, or you'll have a lot of hard feelings.

I have two wish stories, both of which I wasn't at the game for and heard about later. These were back in the previous editions, when there were less restrictions on wishes. Probably the most effective wish I saw a character wished for all the gold in a particular enemy kingdom to turn irrecoverably into wood. Bankrupted them overnight. That became a major plot point over the next few months of gaming. The country instituted paper money, had to abandon an expansionist expedition that was relying on mercenaries. They still had gem and platinum wealth, and silver coinage, but losing all the gold really set them back. What made it a great wish was not just the creativity of the player who thought it up, but also the way the GM ran with it.

The other one I think is cooler, just because it was so pointless. A character gets a ring of wishes, but he thinks its a ring of water-walking or something kinda cool but not super-powerful. The character's are booking passage on a ship, and the GM says the name of the ship is the Kraken. Another player starts in with, "The Kraken, what a stupid name for a ship!" and the player with the ring-- trying to stop the other character from insulting the captain of said ship-- says, "I think 'The Kraken' is a great name for a ship! I wish every ship in the world was named 'The Kraken'!"

That was over a decade ago, and when we get on a ship in that game, its always called 'the Kraken'.

I've only cast one wish in play. It was from a djinn, and the limitation that it had to be used for travel or transport. It had to take someone or something from somewhere to somewhere else. Tiamat had just gotten loose on the prime material, and we wished her back to Hell. That bought us a few months of game time at least.