Short answer: it depends on whether you’re just being “detained” or formally arrested, and what state/federal rules apply—but there are limits.

I’ll break it down in plain English.

1. Brief Detention (Stopped but Not Formally Arrested)

This is when police stop you to ask questions, like during:

• A traffic stop
• A stop-and-frisk
• A quick street investigation

They can only keep you:

• As long as is reasonably necessary to confirm or dispel their suspicion
• Usually this means minutes, not hours

If they drag it out without good reason, a judge could later rule the detention unlawful and throw out evidence.

You can ask politely:

“Am I free to leave, or am I being detained?”

If they say you’re free to go—you can leave.
If they say you’re detained or under arrest—stop talking and ask for a lawyer.

2. After You’re Arrested (Big Difference)

Once you’re formally arrested (not just “held to talk”), the rules are stricter.

In the U.S., for most criminal arrests:

• Police generally must bring you before a judge or magistrate promptly
• For warrantless arrests, the Supreme Court has said you’re usually entitled to a probable cause determination within about 48 hours of arrest in most situations (weekends/holidays can affect this).
• Some states have their own rules like “next court day” or within 24 hours, etc.

If they keep you:

• Days go by and you never see a judge, never get charged, and there’s no warrant or hearing, that can be a serious problem legally.

3. If They Haven’t Charged You Yet

Sometimes police will:

• Arrest you
• Hold you for questioning
• Then release you without filing charges (for now)

If they release you, they might:

• Say the case is still “under investigation,” or
• Tell you you’ll get a summons or court notice later

Whether they can still charge you later depends on statutes of limitations and other rules, but the immediate question of “how long can they hold me now?” usually ends once you’re released.

4. Special Situations

Timing and rules can be different if:

• You’re a juvenile
• There’s an immigration hold (ICE detainer)
• You’re on probation or parole
• It’s a federal case vs. state

In those situations, multiple agencies might be involved, and different timelines can apply.

5. What You Should Do If You’re Being Held

If you are currently being held or this just happened, do this, not that:

Do:

• Clearly say:

“I want a lawyer. I am invoking my right to remain silent.”

• Repeat it if they keep questioning you.
• Give only basic identifying information (name, DOB, address as required).

Don’t:

• Don’t explain “your side of the story” without a lawyer.
• Don’t argue about the law with the officers on the spot.
• Don’t sign anything you don’t understand.

6. You Really Need Local Legal Advice

The exact time limits and procedures depend heavily on:

• The state you’re in
• Whether it’s state or federal
• The specific charge

Because this is about your freedom, you should talk to a local criminal defense lawyer ASAP. If you’re asking this for yourself or someone currently locked up, it’s important to speak to an attorney right away—many will do free initial consultations and can check court records and timing issues immediately.

If you tell me:

• The state you’re in and
• Whether this is about you or someone else in custody