In the Directive Article 4 the definition used is:
(3) ‘abusive court proceedings against public participation’ mean court proceedings which are not brought to genuinely assert or exercise a right, but have as their main purpose the prevention, restriction or penalisation of public participation, frequently exploiting an imbalance of power between the parties, and which pursue unfounded claims. Indications of such a purpose include for example:
(a) the disproportionate, excessive or unreasonable nature of the claim or part thereof, including the excessive dispute value;
(b) the existence of multiple proceedings initiated by the claimant or associated parties in relation to similar matters;
(c) intimidation, harassment or threats on the part of the claimant or the claimant’s representatives, before or during the proceedings, as well as similar conduct by the claimant in similar or concurrent cases;
(d) the use in bad faith of procedural tactics, such as delaying proceedings, fraudulent or abusive forum shopping or the discontinuation of cases at a later stage of the proceedings in bad faith.
In the Model law section 1(4) the definition used is:
an “abusive court proceeding against public participation” means, regardless of intent, a judicial application or pleading that is disproportionate, excessive, unreasonable, causes prejudice to another person, or defeats the ends of justice, particularly if it operates to restrict another person’s public participation on a matter of public interest;