Use PutObjectLegalHold with an AWS SDK or CLI

    /// <summary>
    /// Set or modify a legal hold on an object in an S3 bucket.
    /// </summary>
    /// <param name="bucketName">The bucket of the object.</param>
    /// <param name="objectKey">The key of the object.</param>
    /// <param name="holdStatus">The On or Off status for the legal hold.</param>
    /// <returns>True if successful.</returns>
    public async Task<bool> ModifyObjectLegalHold(string bucketName,
        string objectKey, ObjectLockLegalHoldStatus holdStatus)
    {
        try
        {
            var request = new PutObjectLegalHoldRequest()
            {
                BucketName = bucketName,
                Key = objectKey,
                LegalHold = new ObjectLockLegalHold()
                {
                    Status = holdStatus
                }
            };

            var response = await _amazonS3.PutObjectLegalHoldAsync(request);
            Console.WriteLine($"\tModified legal hold for {objectKey} in {bucketName}.");
            return response.HttpStatusCode == System.Net.HttpStatusCode.OK;
        }
        catch (AmazonS3Exception ex)
        {
            Console.WriteLine($"\tError modifying legal hold: '{ex.Message}'");
            return false;
        }
    }

To apply a Legal Hold to an object

The following put-object-legal-hold example sets a Legal Hold on the object doc1.rtf.

aws s3api put-object-legal-hold \
    --bucket my-bucket-with-object-lock \
    --key doc1.rtf \
    --legal-hold Status=ON

This command produces no output.

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"log"
	"time"

	"github.com/aws/aws-sdk-go-v2/aws"
	"github.com/aws/aws-sdk-go-v2/feature/s3/manager"
	"github.com/aws/aws-sdk-go-v2/service/s3"
	"github.com/aws/aws-sdk-go-v2/service/s3/types"
	"github.com/aws/smithy-go"
)

// S3Actions wraps S3 service actions.
type S3Actions struct {
	S3Client  *s3.Client
	S3Manager *manager.Uploader
}



// PutObjectLegalHold sets the legal hold configuration for an S3 object.
func (actor S3Actions) PutObjectLegalHold(ctx context.Context, bucket string, key string, versionId string, legalHoldStatus types.ObjectLockLegalHoldStatus) error {
	input := &s3.PutObjectLegalHoldInput{
		Bucket: aws.String(bucket),
		Key:    aws.String(key),
		LegalHold: &types.ObjectLockLegalHold{
			Status: legalHoldStatus,
		},
	}
	if versionId != "" {
		input.VersionId = aws.String(versionId)
	}

	_, err := actor.S3Client.PutObjectLegalHold(ctx, input)
	if err != nil {
		var noKey *types.NoSuchKey
		if errors.As(err, &noKey) {
			log.Printf("Object %s does not exist in bucket %s.\n", key, bucket)
			err = noKey
		}
	}

	return err
}

    // Set or modify a legal hold on an object in an S3 bucket.
    public void modifyObjectLegalHold(String bucketName, String objectKey, boolean legalHoldOn) {
        ObjectLockLegalHold legalHold ;
        if (legalHoldOn) {
            legalHold = ObjectLockLegalHold.builder()
                .status(ObjectLockLegalHoldStatus.ON)
                .build();
        } else {
            legalHold = ObjectLockLegalHold.builder()
                .status(ObjectLockLegalHoldStatus.OFF)
                .build();
        }

        PutObjectLegalHoldRequest legalHoldRequest = PutObjectLegalHoldRequest.builder()
            .bucket(bucketName)
            .key(objectKey)
            .legalHold(legalHold)
            .build();

        getClient().putObjectLegalHold(legalHoldRequest) ;
        System.out.println("Modified legal hold for "+ objectKey +" in "+bucketName +".");
    }

import {
  PutObjectLegalHoldCommand,
  S3Client,
  S3ServiceException,
} from "@aws-sdk/client-s3";

/**
 * Apply a legal hold configuration to the specified object.
 * @param {{ bucketName: string, objectKey: string, legalHoldStatus: "ON" | "OFF" }}
 */
export const main = async ({ bucketName, objectKey, legalHoldStatus }) => {
  if (!["OFF", "ON"].includes(legalHoldStatus.toUpperCase())) {
    throw new Error(
      "Invalid parameter. legalHoldStatus must be 'ON' or 'OFF'.",
    );
  }

  const client = new S3Client({});
  const command = new PutObjectLegalHoldCommand({
    Bucket: bucketName,
    Key: objectKey,
    LegalHold: {
      // Set the status to 'ON' to place a legal hold on the object.
      // Set the status to 'OFF' to remove the legal hold.
      Status: legalHoldStatus,
    },
  });

  try {
    await client.send(command);
    console.log(
      `Legal hold status set to "${legalHoldStatus}" for "${objectKey}" in "${bucketName}"`,
    );
  } catch (caught) {
    if (
      caught instanceof S3ServiceException &&
      caught.name === "NoSuchBucket"
    ) {
      console.error(
        `Error from S3 while modifying legal hold status for "${objectKey}" in "${bucketName}". The bucket doesn't exist.`,
      );
    } else if (caught instanceof S3ServiceException) {
      console.error(
        `Error from S3 while modifying legal hold status for "${objectKey}" in "${bucketName}". ${caught.name}: ${caught.message}`,
      );
    } else {
      throw caught;
    }
  }
};

// Call function if run directly
import { parseArgs } from "node:util";
import {
  isMain,
  validateArgs,
} from "@aws-doc-sdk-examples/lib/utils/util-node.js";

const loadArgs = () => {
  const options = {
    bucketName: {
      type: "string",
      required: true,
    },
    objectKey: {
      type: "string",
      required: true,
    },
    legalHoldStatus: {
      type: "string",
      default: "ON",
    },
  };
  const results = parseArgs({ options });
  const { errors } = validateArgs({ options }, results);
  return { errors, results };
};

if (isMain(import.meta.url)) {
  const { errors, results } = loadArgs();
  if (!errors) {
    main(results.values);
  } else {
    console.error(errors.join("\n"));
  }
}

Put an object legal hold.

def set_legal_hold(s3_client, bucket: str, key: str) -> None:
    """
    Set a legal hold on a specific file in a bucket.

    Args:
        s3_client: Boto3 S3 client.
        bucket: The name of the bucket containing the file.
        key: The key of the file to set the legal hold on.
    """
    print()
    logger.info("Setting legal hold on file [%s] in bucket [%s]", key, bucket)
    try:
        before_status = "OFF"
        after_status = "ON"
        s3_client.put_object_legal_hold(
            Bucket=bucket, Key=key, LegalHold={"Status": after_status}
        )
        logger.debug(
            "Legal hold set successfully on file [%s] in bucket [%s]", key, bucket
        )
        _print_legal_hold_update(bucket, key, before_status, after_status)
    except Exception as e:
        logger.error(
            "Failed to set legal hold on file [%s] in bucket [%s]: %s", key, bucket, e
        )