In essence, a thing may declare a person cursable, concomitant with its sovereign rights to declare war, or to declare someone outlaw. Once someone is declared outlaw, if they are found within the vicinity of the community, they may be killed by anyone with impunity, of course. Similarly, once a state of war has been declared with an individual or community, they may be cursed with impunity, because all bets are off at that point. But conversely, a curse is an act of war. It is the psychological / psychic level of warfare that accompanies other levels and forms of warfare. In other words, curses are battle-magic (addressed, for example, in the First Merseburg Charm), and thus appropriate, if at all, if and only if one is completely out of a state of frith or grith with another. (In the second Helgi Hundingsbani, Sigrun curses Dag because he has killed her husband to whom Dag had given oaths.)
Investing curses as a judicial function of the community may be immensely displeasing to modern practitioners of magic who hoped to gain some extralegal means of asserting malevolence or revenge, but such behavior could never be tolerated in a lawful community, because it violates the basic rule of law. In fact, it was never tolerated. The ancient Germanic laws are very clear that maleficia, defined as malevolent magic (and not, as the Christian Church later confused the issue, mixed with acts of contraception and abortion), is a judicial offense, and a crime on its face, punishable by tremendous fines. In other words, a curser is legally responsible to pay damages. It is an injury and therefore a trespass requiring reparation. The problem with the witchcraft trials of the later Christian Church was the violation of due process due to extended imprisonment and torture prior to trial, along with forced confessions, and punishments out of proportion with earlier Germanic fines ; but to take someone to trial for inflicting malevolent magic was not out of the ordinary for Germanic heathen custom.
Most often, curses are actually the property of ill wights. Loki curses the Aesir as he is ousted from Aegir's Hall in Lokasenna. Hyndla, the wolf-riding jotunn-bride, curses Freya in Hyndluljod. Most of those who engage in curses or malevolent magic in the sagas are portrayed as untrustworthy, antisocial fellows whom the community considers a liability, and with good reason. To threaten or intimidate others with the supernatural is an act of aggression that is not consistent with a frithful community, and constitutes a violation of that peace. Further, to engage in cursing (without a state of war having been declared by the thing) is a nithing-act, akin to murder in the sense that it is a cowardly, dishonorable, underhanded attack where the other party doesn't have the chance to defend themselves.
It should be fairly clear that from a historical perspective, the lore bears out the perspective that cursing was allowable only under very limited conditions, and was considered not properly the purvue of the lone individual, but as a judicial function of the community. But beyond the loric and historical perspective, there are rational reasons for not only discouraging cursing, but out-and-out banning it from any community. These have primarily to do with the chilling effect the presence of cursers have on free discourse and debate within a community. Such discourse must be free to speak with impunity, and cannot be restricted by fear of intimidation of any kind. To have practitioners in a community whom others are fearful of irrational reprisal if they feel slighted is to have a community that sanctions some bullying over others. This is certainly not the heathen way. To require, as it were, a "court order" by the community thing prior to cursing sets up a firewall against individual caprice and intimidation by the powerful. Such a firewall is a logical precaution against the rationalizing tendency in human beings, which tends to justify anything, especially if the passions, such as anger or vengeance, are involved. Moreover, it means that one human being all on their own cannot decide crucial issues of luck for another, because individual feelings of being wounded may not match community standards. Let's face it --- everyone knows a person who if you look at them wrong, or stand up and act with some assertiveness and dignity, considers themselves injured by such an ordinary, human act, and heathenism does not tolerate the behavior of such princess-tyrants.
Friends don't let friends curse. Nor, I think, should the presence of known cursers be tolerated. We are called upon by the gods to have high standards, and to create the conditions for a strong and frithful innangards where wisdom can grow, and we can all grow stronger. These conditions are not compatible with a general state of strife. Obviously in order for wisdom to grow, strong levels of critique must be not only tolerated, but encouraged, but this kind of critique is a species of tough love, not of antagonism. Antagonistic strife-stirring, with no intention of building the community so it becomes more worthy of the gods' notice, attention, and luck-sharing, is an act of sabotage against the community. A community must have a certain standard of security in order for good things to prosper and for the general welfare to raise to a level of education that allows wisdom to accumulate. Bullies, slanderers, and curse-mongers diminish the security and freedom of a community, and are saboteurs of its growth into full worth.
To accept the rule of law is to accept the rule of law, period. It does not allow of loopholes, excuses, or attempts to weasel out of responsible, upright behavior, even or especially through supernatural behavior. It implies what Garman Lord has rightfully called a "right good will", or what might simply be called "maturity". This is what a community must foster in order to grow in worth and be a blessing unto the gods. There is no place therein for strife-bearers or curse-mongers.
However, if one does encounter a curse-monger, there are strong spells within heathenism to protect completely a frithful member of the community. First of all, one should remember that Thor himself "bears ill will" (Hyndluljod 4) towards Jotunn troll-wife cursers, and his permission must be obtained for them to even be in his presence (Hyndluljod 4), while oath-breakers, traitors, and carriers of strife make his "rage swell" (Voluspa 29, 30). So even without specific words or formulas, calling upon Thor, who is "mightiest" (Gylfaginning 44), is more than sufficient to completely dissolve a curse. Odin, a master of seidr, knows three mighty songs to dispel any curses : in the third of his eighteen mighty songs he learned from Mimir, he is able to deaden the edges not only of the arms of his foes, but also their wiles, and can restrain them from harm (Havamal 150). With the sixth of these songs (Havamal 153), he is able to turn the hatred of one who pronounces hateful spells or carves harmful runes onto the curser ; and with the tenth song (Havamal 157), any seidr-practitioner who is ham-faring to do ill may be tossed back into their own bodies where they cannot roam and do harm. Moreover, he knows how to stop hostile shot, whether magical or projectile (Havamal 152), and more importantly, how to dispel the general state of hostility that motivates curses and strife into friendliness (Havamal 155). These are good spells whose powers are always useful to humans, but of absolutely no use or power for jotnar or their kind (Havamal 166), and which were invested in the community of men through their rightfully elected kings and noble, excellent jarls (Rigsthula 33, 40 - 42). They are not said to have been generally distributed to humankind as individuals, because they were to be invested in the community as a whole, and therefore invested in those who hold the luck of that community, the elders, the outstanding, and the king. The leaders of a community are always called upon to utter those blessings which dispel the fear of curses, and to do so with an authority that the gods themselves invest in the community through their sacred office as leaders. If such an elder or leader places his luck upon you, you have no need to fear of anyone, no matter how much shibbolethry and hocus-pocus they wave about ; these are powers that come, after all, from the gods. Beyond these powers of protection afforded by Thor, Odin, and Heimdall (through community leadership), the asynior themselves guarantee protection and safety to those who blot to them, no matter how great the need (Fjolsvinnsmal 40). The First Merseburg Charm (http://www.northvegr.org/lore/merseburg/index.php) provides an excellent prayer to the disir who watch over one's luck, to fetter the enemy and impede their armies, while freeing one's own luck from any fetters or curses placed upon it, allowing one to escape from the grasp of one's foes. Moreover, the foremost of the disir of the Vanir, the Vanadis, and, one might say, the princess of the asynior herself utters one of the most powerful dispellers of curses known. We have already discussed in this blog her opposition to that ur-curser herself, Gullveig-Angroboda, and indeed it is not only most likely, but practically certain that "Hyndla" in Hyndluljod is in fact Gullveig. There, when Gullveig threatens to call the harm of Ragnarok down upon Freya, and curses her for her freedom in love, Freya utters words that are most certainly a formula to dispel ill magic. She says there, "Orðheill þín skal engu ráða, þóttú, brúðr jötuns bölvi heitir;" "Your cursing words (or, premonitions) shall come to nothing (literally, shall have no "command" or "authority"), jotunn's bride, though bale you threaten." Finally, Erikr (one of Odr's bynames), on the way to rescue Freya from the giants who had seized her (Voluspa 29), having received mighty spells from his mother, utters a spell so powerful that it is able to not only completely extinguish all the curses thrown against him by the jotnar, but actually shatters the nid-stang they had raised against him : 'In latorem,' inquit, 'gestaminis sui fortuna recidat; nos melior consequatur eventus! Male maleficis cedat, infaustae molis gerulum onus obruat; nobis potiora tribuant omina sospitatem!' (Saxo Grammaticus' History of the Danes, Book Five) ; "On the curser falls the ill luck of what he bears ; while a good, noble, and healthy outcome attends on us! Evil falls back onto the cursers and ill-doers. Let the millstones crush the carriers of this misfortune ; we shall be granted the stronger and more desirable omens of health, safety, and welfare!"
And that is a good way to end this post. Fear not and befriend not the cursers.