The short answer
Personal jurisdiction is a court’s power over a specific defendant. An Illinois court can hear a case against an out-of-state business only if the business has enough claim-related connection to Illinois or consented to jurisdiction.
Where it fits in your case
It is raised at the very start, before or with the first response.
What to expect
Specific jurisdiction turns on whether the defendant directed activity at Illinois and the claim relates to it.
General jurisdiction usually exists only where a company is incorporated or headquartered.
Consent. Forum selection and consent clauses can settle the question.
Waiver. Filing a substantive response first can waive the objection (735 ILCS 5/2-301).
What we need from you
Contracts and terms, where they were signed, and a list of Illinois contacts: visits, shipments, sales, and who started the relationship.
Common misconceptions
“Doing business with an Illinois company is enough.” Emails and calls alone often are not.
“Winning ends the dispute.” The plaintiff can usually refile where the defendant is located.